diff --git a/Demo/DemoChat/Sources/UI/DetailView.swift b/Demo/DemoChat/Sources/UI/DetailView.swift
index 9e2a07e9..3cd119ea 100644
--- a/Demo/DemoChat/Sources/UI/DetailView.swift
+++ b/Demo/DemoChat/Sources/UI/DetailView.swift
@@ -19,7 +19,7 @@ struct DetailView: View {
     @State private var showsModelSelectionSheet = false
     @State private var selectedChatModel: Model = .gpt4_0613
 
-    private let availableChatModels: [Model] = [.gpt3_5Turbo0613, .gpt4_0613]
+    private let availableChatModels: [Model] = [.gpt3_5Turbo, .gpt4_0613]
 
     let conversation: Conversation
     let error: Error?
diff --git a/Demo/DemoChat/Sources/UI/TextToSpeechView.swift b/Demo/DemoChat/Sources/UI/TextToSpeechView.swift
index 459a4423..023548ce 100644
--- a/Demo/DemoChat/Sources/UI/TextToSpeechView.swift
+++ b/Demo/DemoChat/Sources/UI/TextToSpeechView.swift
@@ -15,7 +15,7 @@ public struct TextToSpeechView: View {
     
     @State private var prompt: String = ""
     @State private var voice: AudioSpeechQuery.AudioSpeechVoice = .alloy
-    @State private var speed: Double = 1
+    @State private var speed: Double = AudioSpeechQuery.Speed.normal.rawValue
     @State private var responseFormat: AudioSpeechQuery.AudioSpeechResponseFormat = .mp3
     
     public init(store: SpeechStore) {
@@ -56,7 +56,7 @@ public struct TextToSpeechView: View {
                 HStack {
                     Text("Speed: ")
                     Spacer()
-                    Stepper(value: $speed, in: 0.25...4, step: 0.25) {
+                    Stepper(value: $speed, in: AudioSpeechQuery.Speed.min.rawValue...AudioSpeechQuery.Speed.max.rawValue, step: 0.25) {
                         HStack {
                             Spacer()
                             Text("**\(String(format: "%.2f", speed))**")
diff --git a/Sources/OpenAI/Public/Models/AudioSpeechQuery.swift b/Sources/OpenAI/Public/Models/AudioSpeechQuery.swift
index 36db44a5..f41a91f8 100644
--- a/Sources/OpenAI/Public/Models/AudioSpeechQuery.swift
+++ b/Sources/OpenAI/Public/Models/AudioSpeechQuery.swift
@@ -54,13 +54,7 @@ public struct AudioSpeechQuery: Codable, Equatable {
         case responseFormat = "response_format"
         case speed
     }
-    
-    private enum Constants {
-        static let normalSpeed = 1.0
-        static let maxSpeed = 4.0
-        static let minSpeed = 0.25
-    }
-    
+
     public init(model: Model, input: String, voice: AudioSpeechVoice, responseFormat: AudioSpeechResponseFormat = .mp3, speed: Double?) {
         self.model = AudioSpeechQuery.validateSpeechModel(model)
         self.speed = AudioSpeechQuery.normalizeSpeechSpeed(speed)
@@ -80,13 +74,22 @@ private extension AudioSpeechQuery {
         }
         return inputModel
     }
-    
+}
+
+public extension AudioSpeechQuery {
+
+    enum Speed: Double {
+        case normal = 1.0
+        case max = 4.0
+        case min = 0.25
+    }
+
     static func normalizeSpeechSpeed(_ inputSpeed: Double?) -> String {
-        guard let inputSpeed else { return "\(Constants.normalSpeed)" }
-        let isSpeedOutOfBounds = inputSpeed >= Constants.maxSpeed && inputSpeed <= Constants.minSpeed
+        guard let inputSpeed else { return "\(Self.Speed.normal.rawValue)" }
+        let isSpeedOutOfBounds = inputSpeed <= Self.Speed.min.rawValue || Self.Speed.max.rawValue <= inputSpeed
         guard !isSpeedOutOfBounds else {
             print("[AudioSpeech] Speed value must be between 0.25 and 4.0. Setting value to closest valid.")
-            return inputSpeed < Constants.minSpeed ? "\(Constants.minSpeed)" : "\(Constants.maxSpeed)"
+            return inputSpeed < Self.Speed.min.rawValue ? "\(Self.Speed.min.rawValue)" : "\(Self.Speed.max.rawValue)"
         }
         return "\(inputSpeed)"
     }
diff --git a/Tests/OpenAITests/OpenAITests.swift b/Tests/OpenAITests/OpenAITests.swift
index 8a552b78..b0f2c932 100644
--- a/Tests/OpenAITests/OpenAITests.swift
+++ b/Tests/OpenAITests/OpenAITests.swift
@@ -258,6 +258,30 @@ class OpenAITests: XCTestCase {
         XCTAssertEqual(inError, apiError)
     }
     
+    func testAudioSpeechDoesNotNormalize() async throws {
+        let query = AudioSpeechQuery(model: .tts_1, input: "Hello, world!", voice: .alloy, responseFormat: .mp3, speed: 2.0)
+
+        XCTAssertEqual(query.speed, "\(2.0)")
+    }
+
+    func testAudioSpeechNormalizeNil() async throws {
+        let query = AudioSpeechQuery(model: .tts_1, input: "Hello, world!", voice: .alloy, responseFormat: .mp3, speed: nil)
+
+        XCTAssertEqual(query.speed, "\(1.0)")
+    }
+
+    func testAudioSpeechNormalizeLow() async throws {
+        let query = AudioSpeechQuery(model: .tts_1, input: "Hello, world!", voice: .alloy, responseFormat: .mp3, speed: 0.0)
+
+        XCTAssertEqual(query.speed, "\(0.25)")
+    }
+
+    func testAudioSpeechNormalizeHigh() async throws {
+        let query = AudioSpeechQuery(model: .tts_1, input: "Hello, world!", voice: .alloy, responseFormat: .mp3, speed: 10.0)
+
+        XCTAssertEqual(query.speed, "\(4.0)")
+    }
+
     func testAudioSpeechError() async throws {
         let query = AudioSpeechQuery(model: .tts_1, input: "Hello, world!", voice: .alloy, responseFormat: .mp3, speed: 1.0)
         let inError = APIError(message: "foo", type: "bar", param: "baz", code: "100")