diff --git a/Signal/src/AppDelegate.m b/Signal/src/AppDelegate.m
index 35ea2be66..a8ae4382c 100644
--- a/Signal/src/AppDelegate.m
+++ b/Signal/src/AppDelegate.m
@@ -1107,6 +1107,7 @@ static NSTimeInterval launchStartedAt;
     // If there were any messages in our local queue which we hadn't yet processed.
     [SSKEnvironment.shared.messageReceiver handleAnyUnprocessedEnvelopesAsync];
     [SSKEnvironment.shared.batchMessageProcessor handleAnyUnprocessedEnvelopesAsync];
+    [Environment.shared.audioSession setup];
 
     if (!Environment.shared.preferences.hasGeneratedThumbnails) {
         [self.primaryStorage.newDatabaseConnection
diff --git a/Signal/src/ViewControllers/AppSettings/OWSSoundSettingsViewController.m b/Signal/src/ViewControllers/AppSettings/OWSSoundSettingsViewController.m
index ed1addd87..c218cd34d 100644
--- a/Signal/src/ViewControllers/AppSettings/OWSSoundSettingsViewController.m
+++ b/Signal/src/ViewControllers/AppSettings/OWSSoundSettingsViewController.m
@@ -112,10 +112,10 @@ NS_ASSUME_NONNULL_BEGIN
 - (void)soundWasSelected:(OWSSound)sound
 {
     [self.audioPlayer stop];
-    self.audioPlayer = [OWSSounds audioPlayerForSound:sound];
+    self.audioPlayer = [OWSSounds audioPlayerForSound:sound audioBehavior:OWSAudioBehavior_Playback];
     // Suppress looping in this view.
     self.audioPlayer.isLooping = NO;
-    [self.audioPlayer playWithPlaybackAudioCategory];
+    [self.audioPlayer play];
 
     if (self.currentSound == sound) {
         return;
diff --git a/Signal/src/ViewControllers/ConversationView/Cells/OWSAudioMessageView.h b/Signal/src/ViewControllers/ConversationView/Cells/OWSAudioMessageView.h
index 1d0c98e6e..f7be8be2e 100644
--- a/Signal/src/ViewControllers/ConversationView/Cells/OWSAudioMessageView.h
+++ b/Signal/src/ViewControllers/ConversationView/Cells/OWSAudioMessageView.h
@@ -2,8 +2,6 @@
 //  Copyright (c) 2018 Open Whisper Systems. All rights reserved.
 //
 
-#import "OWSAudioPlayer.h"
-
 NS_ASSUME_NONNULL_BEGIN
 
 @class ConversationStyle;
diff --git a/Signal/src/ViewControllers/ConversationView/ConversationViewController.m b/Signal/src/ViewControllers/ConversationView/ConversationViewController.m
index efe8a7128..15d8d3cc9 100644
--- a/Signal/src/ViewControllers/ConversationView/ConversationViewController.m
+++ b/Signal/src/ViewControllers/ConversationView/ConversationViewController.m
@@ -149,7 +149,7 @@ typedef enum : NSUInteger {
 
 @property (nonatomic) TSThread *thread;
 @property (nonatomic, readonly) YapDatabaseConnection *editingDatabaseConnection;
-@property (nonatomic, readonly) AudioActivity *voiceNoteAudioActivity;
+@property (nonatomic, readonly) OWSAudioActivity *recordVoiceNoteAudioActivity;
 @property (nonatomic, readonly) NSTimeInterval viewControllerCreatedAt;
 
 // These two properties must be updated in lockstep.
@@ -286,9 +286,18 @@ typedef enum : NSUInteger {
     _contactShareViewHelper.delegate = self;
 
     NSString *audioActivityDescription = [NSString stringWithFormat:@"%@ voice note", self.logTag];
-    _voiceNoteAudioActivity = [[AudioActivity alloc] initWithAudioDescription:audioActivityDescription];
+    _recordVoiceNoteAudioActivity = [[OWSAudioActivity alloc] initWithAudioDescription:audioActivityDescription behavior:OWSAudioBehavior_PlayAndRecord];
 }
 
+#pragma mark - Dependencies
+
+- (OWSAudioSession *)audioSession
+{
+    return Environment.shared.audioSession;
+}
+
+#pragma mark
+
 - (void)addNotificationListeners
 {
     [[NSNotificationCenter defaultCenter] addObserver:self
@@ -2229,11 +2238,13 @@ typedef enum : NSUInteger {
         [self.audioAttachmentPlayer stop];
         self.audioAttachmentPlayer = nil;
     }
+
     self.audioAttachmentPlayer =
-        [[OWSAudioPlayer alloc] initWithMediaUrl:attachmentStream.originalMediaURL delegate:viewItem];
+        [[OWSAudioPlayer alloc] initWithMediaUrl:attachmentStream.originalMediaURL audioBehavior:OWSAudioBehavior_AudioMessagePlayback delegate:viewItem];
+    
     // Associate the player with this media adapter.
     self.audioAttachmentPlayer.owner = viewItem;
-    [self.audioAttachmentPlayer playWithPlaybackAudioCategory];
+    [self.audioAttachmentPlayer play];
 }
 
 - (void)didTapTruncatedTextMessage:(id<ConversationViewItem>)conversationItem
@@ -3613,7 +3624,7 @@ typedef enum : NSUInteger {
     NSURL *fileURL = [NSURL fileURLWithPath:filepath];
 
     // Setup audio session
-    BOOL configuredAudio = [OWSAudioSession.shared startRecordingAudioActivity:self.voiceNoteAudioActivity];
+    BOOL configuredAudio = [self.audioSession startAudioActivity:self.recordVoiceNoteAudioActivity];
     if (!configuredAudio) {
         OWSFailDebug(@"Couldn't configure audio session");
         [self cancelVoiceMemo];
@@ -3714,7 +3725,7 @@ typedef enum : NSUInteger {
 - (void)stopRecording
 {
     [self.audioRecorder stop];
-    [OWSAudioSession.shared endAudioActivity:self.voiceNoteAudioActivity];
+    [self.audioSession endAudioActivity:self.recordVoiceNoteAudioActivity];
 }
 
 - (void)cancelRecordingVoiceMemo
diff --git a/Signal/src/ViewControllers/MessageDetailViewController.swift b/Signal/src/ViewControllers/MessageDetailViewController.swift
index 41f0dfb6c..b08d9802d 100644
--- a/Signal/src/ViewControllers/MessageDetailViewController.swift
+++ b/Signal/src/ViewControllers/MessageDetailViewController.swift
@@ -675,12 +675,12 @@ class MessageDetailViewController: OWSViewController, MediaGalleryDataSourceDele
             self.audioAttachmentPlayer = nil
         }
 
-        let audioAttachmentPlayer = OWSAudioPlayer(mediaUrl: mediaURL, delegate: viewItem)
+        let audioAttachmentPlayer = OWSAudioPlayer(mediaUrl: mediaURL, audioBehavior: .audioMessagePlayback, delegate: viewItem)
         self.audioAttachmentPlayer = audioAttachmentPlayer
 
         // Associate the player with this media adapter.
         audioAttachmentPlayer.owner = viewItem
-        audioAttachmentPlayer.playWithPlaybackAudioCategory()
+        audioAttachmentPlayer.play()
     }
 
     func didTapTruncatedTextMessage(_ conversationItem: ConversationViewItem) {
diff --git a/Signal/src/call/CallAudioService.swift b/Signal/src/call/CallAudioService.swift
index 1b627e732..8ce926ce7 100644
--- a/Signal/src/call/CallAudioService.swift
+++ b/Signal/src/call/CallAudioService.swift
@@ -110,8 +110,9 @@ protocol CallAudioServiceDelegate: class {
     private let pulseDuration = 0.2
 
     var audioSession: OWSAudioSession {
-        return OWSAudioSession.shared
+        return Environment.shared.audioSession
     }
+
     var avAudioSession: AVAudioSession {
         return AVAudioSession.sharedInstance()
     }
@@ -396,7 +397,7 @@ protocol CallAudioServiceDelegate: class {
     }
 
     private func play(sound: OWSSound) {
-        guard let newPlayer = OWSSounds.audioPlayer(for: sound) else {
+        guard let newPlayer = OWSSounds.audioPlayer(for: sound, audioBehavior: .call) else {
             owsFailDebug("unable to build player for sound: \(OWSSounds.displayName(for: sound))")
             return
         }
@@ -406,7 +407,7 @@ protocol CallAudioServiceDelegate: class {
         // we're playing the same sound, since the player is memoized on the sound instance, we'd otherwise 
         // stop the sound we just started.
         self.currentPlayer?.stop()
-        newPlayer.playWithCurrentAudioCategory()
+        newPlayer.play()
         self.currentPlayer = newPlayer
     }
 
diff --git a/Signal/src/call/NonCallKitCallUIAdaptee.swift b/Signal/src/call/NonCallKitCallUIAdaptee.swift
index 930fb4f9a..7508345ab 100644
--- a/Signal/src/call/NonCallKitCallUIAdaptee.swift
+++ b/Signal/src/call/NonCallKitCallUIAdaptee.swift
@@ -26,13 +26,22 @@ class NonCallKitCallUIAdaptee: NSObject, CallUIAdaptee {
         super.init()
     }
 
+    // MARK: Dependencies
+
+    var audioSession: OWSAudioSession {
+        return Environment.shared.audioSession
+    }
+
+    // MARK: 
+
     func startOutgoingCall(handle: String) -> SignalCall {
         AssertIsOnMainThread()
 
         let call = SignalCall.outgoingCall(localId: UUID(), remotePhoneNumber: handle)
 
         // make sure we don't terminate audio session during call
-        OWSAudioSession.shared.startAudioActivity(call.audioActivity)
+        let success = self.audioSession.startAudioActivity(call.audioActivity)
+        assert(success)
 
         self.callService.handleOutgoingCall(call).retainUntilComplete()
 
@@ -84,7 +93,7 @@ class NonCallKitCallUIAdaptee: NSObject, CallUIAdaptee {
             return
         }
 
-        OWSAudioSession.shared.isRTCAudioEnabled = true
+        self.audioSession.isRTCAudioEnabled = true
         self.callService.handleAnswerCall(call)
     }
 
@@ -118,7 +127,7 @@ class NonCallKitCallUIAdaptee: NSObject, CallUIAdaptee {
     func recipientAcceptedCall(_ call: SignalCall) {
         AssertIsOnMainThread()
 
-        OWSAudioSession.shared.isRTCAudioEnabled = true
+        self.audioSession.isRTCAudioEnabled = true
     }
 
     func localHangupCall(_ call: SignalCall) {
diff --git a/Signal/src/call/SignalCall.swift b/Signal/src/call/SignalCall.swift
index 51a018803..370960238 100644
--- a/Signal/src/call/SignalCall.swift
+++ b/Signal/src/call/SignalCall.swift
@@ -161,7 +161,7 @@ protocol CallObserver: class {
         self.state = state
         self.remotePhoneNumber = remotePhoneNumber
         self.thread = TSContactThread.getOrCreateThread(contactId: remotePhoneNumber)
-        self.audioActivity = AudioActivity(audioDescription: "[SignalCall] with \(remotePhoneNumber)")
+        self.audioActivity = AudioActivity(audioDescription: "[SignalCall] with \(remotePhoneNumber)", behavior: .call)
     }
 
     // A string containing the three identifiers for this call.
diff --git a/Signal/src/call/Speakerbox/CallKitCallUIAdaptee.swift b/Signal/src/call/Speakerbox/CallKitCallUIAdaptee.swift
index 76b17e869..6e0970623 100644
--- a/Signal/src/call/Speakerbox/CallKitCallUIAdaptee.swift
+++ b/Signal/src/call/Speakerbox/CallKitCallUIAdaptee.swift
@@ -88,7 +88,7 @@ final class CallKitCallUIAdaptee: NSObject, CallUIAdaptee, CXProviderDelegate {
 
         self.provider = type(of: self).sharedProvider(useSystemCallLog: useSystemCallLog)
 
-        self.audioActivity = AudioActivity(audioDescription: "[CallKitCallUIAdaptee]")
+        self.audioActivity = AudioActivity(audioDescription: "[CallKitCallUIAdaptee]", behavior: .call)
         self.showNamesOnCallScreen = showNamesOnCallScreen
 
         super.init()
@@ -98,6 +98,12 @@ final class CallKitCallUIAdaptee: NSObject, CallUIAdaptee, CXProviderDelegate {
         self.provider.setDelegate(self, queue: nil)
     }
 
+    // MARK: Dependencies
+
+    var audioSession: OWSAudioSession {
+        return Environment.shared.audioSession
+    }
+
     // MARK: CallUIAdaptee
 
     func startOutgoingCall(handle: String) -> SignalCall {
@@ -107,7 +113,7 @@ final class CallKitCallUIAdaptee: NSObject, CallUIAdaptee, CXProviderDelegate {
         let call = SignalCall.outgoingCall(localId: UUID(), remotePhoneNumber: handle)
 
         // make sure we don't terminate audio session during call
-        OWSAudioSession.shared.startAudioActivity(call.audioActivity)
+        self.audioSession.startAudioActivity(call.audioActivity)
 
         // Add the new outgoing call to the app's list of calls.
         // So we can find it in the provider delegate callbacks.
@@ -379,16 +385,16 @@ final class CallKitCallUIAdaptee: NSObject, CallUIAdaptee, CXProviderDelegate {
 
         Logger.debug("Received")
 
-        OWSAudioSession.shared.startAudioActivity(self.audioActivity)
-        OWSAudioSession.shared.isRTCAudioEnabled = true
+        self.audioSession.startAudioActivity(self.audioActivity)
+        self.audioSession.isRTCAudioEnabled = true
     }
 
     func provider(_ provider: CXProvider, didDeactivate audioSession: AVAudioSession) {
         AssertIsOnMainThread()
 
         Logger.debug("Received")
-        OWSAudioSession.shared.isRTCAudioEnabled = false
-        OWSAudioSession.shared.endAudioActivity(self.audioActivity)
+        self.audioSession.isRTCAudioEnabled = false
+        self.audioSession.endAudioActivity(self.audioActivity)
     }
 
     // MARK: - Util
diff --git a/Signal/src/call/UserInterface/CallUIAdapter.swift b/Signal/src/call/UserInterface/CallUIAdapter.swift
index c4d274987..a7cd703dd 100644
--- a/Signal/src/call/UserInterface/CallUIAdapter.swift
+++ b/Signal/src/call/UserInterface/CallUIAdapter.swift
@@ -129,11 +129,19 @@ extension CallUIAdaptee {
         callService.addObserverAndSyncState(observer: self)
     }
 
+    // MARK: Dependencies
+
+    var audioSession: OWSAudioSession {
+        return Environment.shared.audioSession
+    }
+
+    // MARK: 
+
     internal func reportIncomingCall(_ call: SignalCall, thread: TSContactThread) {
         AssertIsOnMainThread()
 
         // make sure we don't terminate audio session during call
-        OWSAudioSession.shared.startAudioActivity(call.audioActivity)
+        audioSession.startAudioActivity(call.audioActivity)
 
         let callerName = self.contactsManager.displayName(forPhoneIdentifier: call.remotePhoneNumber)
         adaptee.reportIncomingCall(call, callerName: callerName)
@@ -181,7 +189,7 @@ extension CallUIAdaptee {
         AssertIsOnMainThread()
 
         if let call = call {
-            OWSAudioSession.shared.endAudioActivity(call.audioActivity)
+            self.audioSession.endAudioActivity(call.audioActivity)
         }
     }
 
diff --git a/SignalMessaging/ViewControllers/MediaMessageView.swift b/SignalMessaging/ViewControllers/MediaMessageView.swift
index 0c84e23c8..02e7b1a51 100644
--- a/SignalMessaging/ViewControllers/MediaMessageView.swift
+++ b/SignalMessaging/ViewControllers/MediaMessageView.swift
@@ -131,7 +131,7 @@ public class MediaMessageView: UIView, OWSAudioPlayerDelegate {
             return
         }
 
-        audioPlayer = OWSAudioPlayer(mediaUrl: dataUrl, delegate: self)
+        audioPlayer = OWSAudioPlayer(mediaUrl: dataUrl, audioBehavior: .playback, delegate: self)
 
         var subviews = [UIView]()
 
diff --git a/SignalMessaging/attachments/OWSVideoPlayer.swift b/SignalMessaging/attachments/OWSVideoPlayer.swift
index 2ba75aac6..c32e899fd 100644
--- a/SignalMessaging/attachments/OWSVideoPlayer.swift
+++ b/SignalMessaging/attachments/OWSVideoPlayer.swift
@@ -22,7 +22,7 @@ public class OWSVideoPlayer: NSObject {
 
     @objc init(url: URL) {
         self.avPlayer = AVPlayer(url: url)
-        self.audioActivity = AudioActivity(audioDescription: "[OWSVideoPlayer] url:\(url)")
+        self.audioActivity = AudioActivity(audioDescription: "[OWSVideoPlayer] url:\(url)", behavior: .playback)
 
         super.init()
 
@@ -32,17 +32,24 @@ public class OWSVideoPlayer: NSObject {
                                                object: avPlayer.currentItem)
     }
 
+    // MARK: Dependencies
+
+    var audioSession: OWSAudioSession {
+        return Environment.shared.audioSession
+    }
+
     // MARK: Playback Controls
 
     @objc
     public func pause() {
         avPlayer.pause()
-        OWSAudioSession.shared.endAudioActivity(self.audioActivity)
+        audioSession.endAudioActivity(self.audioActivity)
     }
 
     @objc
     public func play() {
-        OWSAudioSession.shared.startPlaybackAudioActivity(self.audioActivity)
+        let success = audioSession.startAudioActivity(self.audioActivity)
+        assert(success)
 
         guard let item = avPlayer.currentItem else {
             owsFailDebug("video player item was unexpectedly nil")
@@ -61,7 +68,7 @@ public class OWSVideoPlayer: NSObject {
     public func stop() {
         avPlayer.pause()
         avPlayer.seek(to: kCMTimeZero)
-        OWSAudioSession.shared.endAudioActivity(self.audioActivity)
+        audioSession.endAudioActivity(self.audioActivity)
     }
 
     @objc(seekToTime:)
@@ -74,6 +81,6 @@ public class OWSVideoPlayer: NSObject {
     @objc
     private func playerItemDidPlayToCompletion(_ notification: Notification) {
         self.delegate?.videoPlayerDidPlayToCompletion(self)
-        OWSAudioSession.shared.endAudioActivity(self.audioActivity)
+        audioSession.endAudioActivity(self.audioActivity)
     }
 }
diff --git a/SignalMessaging/environment/AppSetup.m b/SignalMessaging/environment/AppSetup.m
index 85f476cbe..5ad9cafa4 100644
--- a/SignalMessaging/environment/AppSetup.m
+++ b/SignalMessaging/environment/AppSetup.m
@@ -83,14 +83,16 @@ NS_ASSUME_NONNULL_BEGIN
             [[OWSOutgoingReceiptManager alloc] initWithPrimaryStorage:primaryStorage];
 
         OWSSyncManager *syncManager = [[OWSSyncManager alloc] initDefault];
+
+        OWSAudioSession *audioSession = [OWSAudioSession new];
         OWSSounds *sounds = [[OWSSounds alloc] initWithPrimaryStorage:primaryStorage];
         LockInteractionController *lockInteractionController = [[LockInteractionController alloc] initDefault];
         OWSWindowManager *windowManager = [[OWSWindowManager alloc] initDefault];
-
-        [Environment setShared:[[Environment alloc] initWithPreferences:preferences
-                                                                 sounds:sounds
-                                              lockInteractionController:lockInteractionController
-                                                          windowManager:windowManager]];
+        [Environment setShared:[[Environment alloc] initWithAudioSession:audioSession
+                                                             preferences:preferences
+                                                                  sounds:sounds
+                                               lockInteractionController:lockInteractionController
+                                                           windowManager:windowManager]];
 
         [SSKEnvironment setShared:[[SSKEnvironment alloc] initWithContactsManager:contactsManager
                                                                     messageSender:messageSender
diff --git a/SignalMessaging/environment/Environment.h b/SignalMessaging/environment/Environment.h
index 0a854ab0b..ee3fadd1f 100644
--- a/SignalMessaging/environment/Environment.h
+++ b/SignalMessaging/environment/Environment.h
@@ -5,6 +5,7 @@
 #import <SignalServiceKit/SSKEnvironment.h>
 
 @class LockInteractionController;
+@class OWSAudioSession;
 @class OWSContactsManager;
 @class OWSPreferences;
 @class OWSSounds;
@@ -17,16 +18,18 @@
  * It also handles network configuration for testing/deployment server configurations.
  *
  **/
-// TODO: Rename to AppEnvironment?
+// TODO: Rename to SMGEnvironment?
 @interface Environment : NSObject
 
 - (instancetype)init NS_UNAVAILABLE;
 
-- (instancetype)initWithPreferences:(OWSPreferences *)preferences
-                             sounds:(OWSSounds *)sounds
-          lockInteractionController:(LockInteractionController *)lockInteractionController
-                      windowManager:(OWSWindowManager *)windowManager;
+- (instancetype)initWithAudioSession:(OWSAudioSession *)audioSession
+                         preferences:(OWSPreferences *)preferences
+                              sounds:(OWSSounds *)sounds
+           lockInteractionController:(LockInteractionController *)lockInteractionController
+                       windowManager:(OWSWindowManager *)windowManager;
 
+@property (nonatomic, readonly) OWSAudioSession *audioSession;
 @property (nonatomic, readonly) OWSContactsManager *contactsManager;
 @property (nonatomic, readonly) OWSPreferences *preferences;
 @property (nonatomic, readonly) OWSSounds *sounds;
diff --git a/SignalMessaging/environment/Environment.m b/SignalMessaging/environment/Environment.m
index 544b09267..0a534c43f 100644
--- a/SignalMessaging/environment/Environment.m
+++ b/SignalMessaging/environment/Environment.m
@@ -11,6 +11,7 @@ static Environment *sharedEnvironment = nil;
 
 @interface Environment ()
 
+@property (nonatomic) OWSAudioSession *audioSession;
 @property (nonatomic) OWSContactsManager *contactsManager;
 @property (nonatomic) OWSPreferences *preferences;
 @property (nonatomic) OWSSounds *sounds;
@@ -47,20 +48,24 @@ static Environment *sharedEnvironment = nil;
     sharedEnvironment = nil;
 }
 
-- (instancetype)initWithPreferences:(OWSPreferences *)preferences
-                             sounds:(OWSSounds *)sounds
-          lockInteractionController:(LockInteractionController *)lockInteractionController
-                      windowManager:(OWSWindowManager *)windowManager {
+- (instancetype)initWithAudioSession:(OWSAudioSession *)audioSession
+                         preferences:(OWSPreferences *)preferences
+                              sounds:(OWSSounds *)sounds
+           lockInteractionController:(LockInteractionController *)lockInteractionController
+                       windowManager:(OWSWindowManager *)windowManager
+{
     self = [super init];
     if (!self) {
         return self;
     }
 
+    OWSAssertDebug(audioSession);
     OWSAssertDebug(preferences);
     OWSAssertDebug(sounds);
     OWSAssertDebug(lockInteractionController);
     OWSAssertDebug(windowManager);
 
+    _audioSession = audioSession;
     _preferences = preferences;
     _sounds = sounds;
     _lockInteractionController = lockInteractionController;
diff --git a/SignalMessaging/environment/OWSAudioSession.swift b/SignalMessaging/environment/OWSAudioSession.swift
index ee0d1236c..ef4868558 100644
--- a/SignalMessaging/environment/OWSAudioSession.swift
+++ b/SignalMessaging/environment/OWSAudioSession.swift
@@ -5,102 +5,118 @@
 import Foundation
 import WebRTC
 
-@objc
+@objc(OWSAudioActivity)
 public class AudioActivity: NSObject {
     let audioDescription: String
 
-    override public var description: String {
-        return "<\(self.logTag) audioDescription: \"\(audioDescription)\">"
-    }
+    let behavior: OWSAudioBehavior
 
     @objc
-    public init(audioDescription: String) {
+    public init(audioDescription: String, behavior: OWSAudioBehavior) {
         self.audioDescription = audioDescription
+        self.behavior = behavior
     }
 
     deinit {
-        OWSAudioSession.shared.ensureAudioSessionActivationStateAfterDelay()
+        audioSession.ensureAudioSessionActivationStateAfterDelay()
+    }
+
+    // MARK: Dependencies
+
+    var audioSession: OWSAudioSession {
+        return Environment.shared.audioSession
+    }
+
+    // MARK: 
+
+    override public var description: String {
+        return "<\(self.logTag) audioDescription: \"\(audioDescription)\">"
     }
 }
 
 @objc
 public class OWSAudioSession: NSObject {
 
-    // Force singleton access
-    @objc public static let shared = OWSAudioSession()
-    private override init() {}
-    private let avAudioSession = AVAudioSession.sharedInstance()
+    @objc
+    public func setup() {
+        NotificationCenter.default.addObserver(self, selector: #selector(proximitySensorStateDidChange(notification:)), name: .UIDeviceProximityStateDidChange, object: nil)
+    }
 
-    private var currentActivities: [Weak<AudioActivity>] = []
+    // MARK: Dependencies
 
-    // Respects hardware mute switch, plays through external speaker, mixes with backround audio
-    // appropriate for foreground sound effects.
-    @objc
-    public func startAmbientAudioActivity(_ audioActivity: AudioActivity) {
-        Logger.debug("")
+    private let avAudioSession = AVAudioSession.sharedInstance()
 
-        objc_sync_enter(self)
-        defer { objc_sync_exit(self) }
+    private let device = UIDevice.current
 
-        startAudioActivity(audioActivity)
-        guard currentActivities.count == 1 else {
-            // We don't want to clobber the audio capabilities configured by (e.g.) media playback or an in-progress call
-            Logger.info("not touching audio session since another currentActivity exists.")
-            return
-        }
+    // MARK: 
 
-        do {
-            try avAudioSession.setCategory(AVAudioSessionCategoryAmbient)
-        } catch {
-            owsFailDebug("failed with error: \(error)")
-        }
+    private var currentActivities: [Weak<AudioActivity>] = []
+    var aggregateBehaviors: Set<OWSAudioBehavior> {
+        return Set(self.currentActivities.compactMap { $0.value?.behavior })
     }
 
-    // Ignores hardware mute switch, plays through external speaker
     @objc
-    public func startPlaybackAudioActivity(_ audioActivity: AudioActivity) {
-        Logger.debug("")
+    public func startAudioActivity(_ audioActivity: AudioActivity) -> Bool {
+        Logger.debug("with \(audioActivity)")
 
         objc_sync_enter(self)
         defer { objc_sync_exit(self) }
 
-        startAudioActivity(audioActivity)
+        self.currentActivities.append(Weak(value: audioActivity))
 
         do {
-            try avAudioSession.setCategory(AVAudioSessionCategoryPlayback)
+            if aggregateBehaviors.contains(.call) {
+                // Do nothing while on a call.
+                // WebRTC/CallAudioService manages call audio
+                // Eventually it would be nice to consolidate more of the audio
+                // session handling.
+            } else {
+                if aggregateBehaviors.contains(.playAndRecord) {
+                    assert(avAudioSession.recordPermission() == .granted)
+                    try avAudioSession.setCategory(AVAudioSessionCategoryRecord)
+                } else if aggregateBehaviors.contains(.audioMessagePlayback) {
+                    try ensureCategoryForProximityState()
+                } else if aggregateBehaviors.contains(.playback) {
+                    try avAudioSession.setCategory(AVAudioSessionCategoryPlayback)
+                } else {
+                    owsFailDebug("no category option specified. Leaving category untouched.")
+                }
+
+                if aggregateBehaviors.contains(.audioMessagePlayback) {
+                    self.device.isProximityMonitoringEnabled = true
+                } else {
+                    self.device.isProximityMonitoringEnabled = false
+                }
+            }
+
+            return true
         } catch {
             owsFailDebug("failed with error: \(error)")
+            return false
         }
     }
 
     @objc
-    public func startRecordingAudioActivity(_ audioActivity: AudioActivity) -> Bool {
-        Logger.debug("")
-
-        objc_sync_enter(self)
-        defer { objc_sync_exit(self) }
-
-        assert(avAudioSession.recordPermission() == .granted)
-
-        startAudioActivity(audioActivity)
-
+    func proximitySensorStateDidChange(notification: Notification) {
         do {
-            try avAudioSession.setCategory(AVAudioSessionCategoryRecord)
-            return true
+            try ensureCategoryForProximityState()
         } catch {
-            owsFailDebug("failed with error: \(error)")
-            return false
+            owsFailDebug("error in response to proximity change: \(error)")
         }
     }
 
-    @objc
-    public func startAudioActivity(_ audioActivity: AudioActivity) {
-        Logger.debug("with \(audioActivity)")
-
-        objc_sync_enter(self)
-        defer { objc_sync_exit(self) }
+    func ensureCategoryForProximityState() throws {
+        if aggregateBehaviors.contains(.audioMessagePlayback) {
+            if self.device.proximityState {
+                Logger.debug("proximityState: true")
 
-        self.currentActivities.append(Weak(value: audioActivity))
+                try avAudioSession.setCategory(AVAudioSessionCategoryPlayAndRecord)
+                try avAudioSession.overrideOutputAudioPort(.none)
+            } else {
+                Logger.debug("proximityState: false")
+                try avAudioSession.setCategory(AVAudioSessionCategoryPlayback)
+            }
+        }
     }
 
     @objc
@@ -111,6 +127,11 @@ public class OWSAudioSession: NSObject {
         defer { objc_sync_exit(self) }
 
         currentActivities = currentActivities.filter { return $0.value != audioActivity }
+        do {
+            try ensureCategoryForProximityState()
+        } catch {
+            owsFailDebug("error in ensureProximityState: \(error)")
+        }
         ensureAudioSessionActivationStateAfterDelay()
     }
 
diff --git a/SignalMessaging/environment/OWSSounds.h b/SignalMessaging/environment/OWSSounds.h
index 4cee5e581..f7ff36072 100644
--- a/SignalMessaging/environment/OWSSounds.h
+++ b/SignalMessaging/environment/OWSSounds.h
@@ -2,6 +2,7 @@
 //  Copyright (c) 2018 Open Whisper Systems. All rights reserved.
 //
 
+#import "OWSAudioPlayer.h"
 #import <AudioToolbox/AudioServices.h>
 
 NS_ASSUME_NONNULL_BEGIN
@@ -68,7 +69,8 @@ typedef NS_ENUM(NSUInteger, OWSSound) {
 
 #pragma mark - AudioPlayer
 
-+ (nullable OWSAudioPlayer *)audioPlayerForSound:(OWSSound)sound;
++ (nullable OWSAudioPlayer *)audioPlayerForSound:(OWSSound)sound
+                                   audioBehavior:(OWSAudioBehavior)audioBehavior;
 
 @end
 
diff --git a/SignalMessaging/environment/OWSSounds.m b/SignalMessaging/environment/OWSSounds.m
index 3ef0bf1da..506b7bd8e 100644
--- a/SignalMessaging/environment/OWSSounds.m
+++ b/SignalMessaging/environment/OWSSounds.m
@@ -375,17 +375,13 @@ NSString *const kOWSSoundsStorageGlobalNotificationKey = @"kOWSSoundsStorageGlob
 }
 
 + (nullable OWSAudioPlayer *)audioPlayerForSound:(OWSSound)sound
+                                 audioBehavior:(OWSAudioBehavior)audioBehavior;
 {
-    return [self audioPlayerForSound:sound quiet:NO];
-}
-
-+ (nullable OWSAudioPlayer *)audioPlayerForSound:(OWSSound)sound quiet:(BOOL)quiet
-{
-    NSURL *_Nullable soundURL = [OWSSounds soundURLForSound:sound quiet:(BOOL)quiet];
+    NSURL *_Nullable soundURL = [OWSSounds soundURLForSound:sound quiet:NO];
     if (!soundURL) {
         return nil;
     }
-    OWSAudioPlayer *player = [[OWSAudioPlayer alloc] initWithMediaUrl:soundURL];
+    OWSAudioPlayer *player = [[OWSAudioPlayer alloc] initWithMediaUrl:soundURL audioBehavior:audioBehavior];
     if ([self shouldAudioPlayerLoopForSound:sound]) {
         player.isLooping = YES;
     }
diff --git a/SignalMessaging/utils/OWSAudioPlayer.h b/SignalMessaging/utils/OWSAudioPlayer.h
index 98a9a2f13..93353c63c 100644
--- a/SignalMessaging/utils/OWSAudioPlayer.h
+++ b/SignalMessaging/utils/OWSAudioPlayer.h
@@ -21,6 +21,14 @@ typedef NS_ENUM(NSInteger, AudioPlaybackState) {
 
 #pragma mark -
 
+typedef NS_ENUM(NSUInteger, OWSAudioBehavior) {
+    OWSAudioBehavior_Unknown,
+    OWSAudioBehavior_Playback,
+    OWSAudioBehavior_AudioMessagePlayback,
+    OWSAudioBehavior_PlayAndRecord,
+    OWSAudioBehavior_Call,
+};
+
 @interface OWSAudioPlayer : NSObject
 
 @property (nonatomic, readonly, weak) id<OWSAudioPlayerDelegate> delegate;
@@ -31,16 +39,13 @@ typedef NS_ENUM(NSInteger, AudioPlaybackState) {
 
 @property (nonatomic) BOOL isLooping;
 
-- (instancetype)initWithMediaUrl:(NSURL *)mediaUrl;
-
-- (instancetype)initWithMediaUrl:(NSURL *)mediaUrl delegate:(id<OWSAudioPlayerDelegate>)delegate;
-
-// respects silent switch
-- (void)playWithCurrentAudioCategory;
+- (instancetype)initWithMediaUrl:(NSURL *)mediaUrl audioBehavior:(OWSAudioBehavior)audioBehavior;
 
-// will ensure sound is audible, even if silent switch is enabled
-- (void)playWithPlaybackAudioCategory;
+- (instancetype)initWithMediaUrl:(NSURL *)mediaUrl
+                     audioBehavior:(OWSAudioBehavior)audioBehavior
+                        delegate:(id<OWSAudioPlayerDelegate>)delegate;
 
+- (void)play;
 - (void)pause;
 - (void)stop;
 - (void)togglePlayState;
diff --git a/SignalMessaging/utils/OWSAudioPlayer.m b/SignalMessaging/utils/OWSAudioPlayer.m
index 9cc8dec90..e44963ef4 100644
--- a/SignalMessaging/utils/OWSAudioPlayer.m
+++ b/SignalMessaging/utils/OWSAudioPlayer.m
@@ -35,7 +35,7 @@ NS_ASSUME_NONNULL_BEGIN
 @property (nonatomic, readonly) NSURL *mediaUrl;
 @property (nonatomic, nullable) AVAudioPlayer *audioPlayer;
 @property (nonatomic, nullable) NSTimer *audioPlayerPoller;
-@property (nonatomic, readonly) AudioActivity *audioActivity;
+@property (nonatomic, readonly) OWSAudioActivity *audioActivity;
 
 @end
 
@@ -44,11 +44,14 @@ NS_ASSUME_NONNULL_BEGIN
 @implementation OWSAudioPlayer
 
 - (instancetype)initWithMediaUrl:(NSURL *)mediaUrl
+                   audioBehavior:(OWSAudioBehavior)audioBehavior
 {
-    return [self initWithMediaUrl:mediaUrl delegate:[OWSAudioPlayerDelegateStub new]];
+    return [self initWithMediaUrl:mediaUrl audioBehavior:audioBehavior delegate:[OWSAudioPlayerDelegateStub new]];
 }
 
-- (instancetype)initWithMediaUrl:(NSURL *)mediaUrl delegate:(id<OWSAudioPlayerDelegate>)delegate
+- (instancetype)initWithMediaUrl:(NSURL *)mediaUrl
+                        audioBehavior:(OWSAudioBehavior)audioBehavior
+                        delegate:(id<OWSAudioPlayerDelegate>)delegate
 {
     self = [super init];
     if (!self) {
@@ -58,11 +61,11 @@ NS_ASSUME_NONNULL_BEGIN
     OWSAssertDebug(mediaUrl);
     OWSAssertDebug(delegate);
 
-    _delegate = delegate;
     _mediaUrl = mediaUrl;
+    _delegate = delegate;
 
     NSString *audioActivityDescription = [NSString stringWithFormat:@"%@ %@", self.logTag, self.mediaUrl];
-    _audioActivity = [[AudioActivity alloc] initWithAudioDescription:audioActivityDescription];
+    _audioActivity = [[OWSAudioActivity alloc] initWithAudioDescription:audioActivityDescription behavior:audioBehavior];
 
     [[NSNotificationCenter defaultCenter] addObserver:self
                                              selector:@selector(applicationDidEnterBackground:)
@@ -81,6 +84,15 @@ NS_ASSUME_NONNULL_BEGIN
     [self stop];
 }
 
+#pragma mark - Dependencies
+
+- (OWSAudioSession *)audioSession
+{
+    return Environment.shared.audioSession;
+}
+
+#pragma mark
+
 - (void)applicationDidEnterBackground:(NSNotification *)notification
 {
     [self stop];
@@ -88,25 +100,21 @@ NS_ASSUME_NONNULL_BEGIN
 
 #pragma mark - Methods
 
-- (void)playWithCurrentAudioCategory
+- (void)play
 {
-    OWSAssertIsOnMainThread();
-    [OWSAudioSession.shared startAudioActivity:self.audioActivity];
 
-    [self play];
+    // get current audio activity
+    OWSAssertIsOnMainThread();
+    [self playWithAudioActivity:self.audioActivity];
 }
 
-- (void)playWithPlaybackAudioCategory
+- (void)playWithAudioActivity:(OWSAudioActivity *)audioActivity
 {
     OWSAssertIsOnMainThread();
-    [OWSAudioSession.shared startPlaybackAudioActivity:self.audioActivity];
 
-    [self play];
-}
+    BOOL success = [self.audioSession startAudioActivity:audioActivity];
+    OWSAssertDebug(success);
 
-- (void)play
-{
-    OWSAssertIsOnMainThread();
     OWSAssertDebug(self.mediaUrl);
     OWSAssertDebug([self.delegate audioPlaybackState] != AudioPlaybackState_Playing);
 
@@ -157,7 +165,7 @@ NS_ASSUME_NONNULL_BEGIN
     [self.audioPlayerPoller invalidate];
     [self.delegate setAudioProgress:(CGFloat)[self.audioPlayer currentTime] duration:(CGFloat)[self.audioPlayer duration]];
 
-    [OWSAudioSession.shared endAudioActivity:self.audioActivity];
+    [self endAudioActivities];
     [DeviceSleepManager.sharedInstance removeBlockWithBlockObject:self];
 }
 
@@ -170,10 +178,15 @@ NS_ASSUME_NONNULL_BEGIN
     [self.audioPlayerPoller invalidate];
     [self.delegate setAudioProgress:0 duration:0];
 
-    [OWSAudioSession.shared endAudioActivity:self.audioActivity];
+    [self endAudioActivities];
     [DeviceSleepManager.sharedInstance removeBlockWithBlockObject:self];
 }
 
+- (void)endAudioActivities
+{
+    [self.audioSession endAudioActivity:self.audioActivity];
+}
+
 - (void)togglePlayState
 {
     OWSAssertIsOnMainThread();
@@ -181,7 +194,7 @@ NS_ASSUME_NONNULL_BEGIN
     if (self.delegate.audioPlaybackState == AudioPlaybackState_Playing) {
         [self pause];
     } else {
-        [self play];
+        [self playWithAudioActivity:self.audioActivity];
     }
 }