{"schema_version":"1.1","default_voice":"af_heart","controls":{"voice":["af_heart","af_bella","bf_emma","bf_alice","bm_george","am_michael","am_fenrir"],"response_format":["mp3"],"speed":[1],"max_input_characters":1000,"emotion_control":false},"agent_guidance":["Use listening_assessment delivery tags and suggested uses as subjective human guidance, not measured facts or emotion controls.","Filter language/accent first, then match requested pitch/pace using numeric values and relative tags.","Use observed passage ranges to avoid treating small differences as decisive.","Do not assume masculine means low-pitched or that pitch variation implies happiness, sadness or expressiveness.","Warmth, mood and age are unassessed; null is unknown, not neutral.","For an explicit emotion request, explain that emotion control is unavailable rather than promising it.","Use af_heart (Hazel) when no preference is supplied; catalogue and sample requests never require payment."],"voices":[{"id":"af_heart","name":"Hazel","language":"en-US","accent":"American English","sample_url":"/v1/audio/voices/af_heart/sample","description":"American English. Natural, informative and instructional. Measured middle pitch and mid-range pace relative to these seven voices at normal speed.","listening_assessment":{"reviewed_at":"2026-09-09","reviewer":"service_owner","basis":"Human listening assessment of supplied synthetic voice samples","limitations":"Subjective assessment by one listener; delivery may change with text. Suggested uses are recommendations, not validated performance guarantees.","summary":"Natural, informative and instructional.","naturalness":"natural","delivery_tags":["informative","instructional"],"suggested_uses":["narration","general_use","instructions"]},"acoustics":{"pitch_median_hz":192.9,"pitch_p10_hz":164.3,"pitch_p90_hz":257.3,"pitch_variation_semitones":7.8,"estimated_wpm":187.5,"passage_median_pitch_hz_range":[191.1,195.3],"passage_wpm_range":[163.5,221.9]},"relative_tags":{"comparison_group":"catalogue-7-at-speed-1","pitch":"middle","pace":"mid-range","pitch_variation":"middle"},"subjective_traits":{"warmth":null,"mood":null,"perceived_age":null,"status":"Warmth, mood and age not rated; human delivery descriptions are in listening_assessment"},"emotion_control":false,"selection_guidance":{"basis":"conditional heuristic, not a validated suitability rating","human_suggested_uses":["narration","general_use","instructions"],"human_delivery_tags":["informative","instructional"],"text":"Consider when a caller requests american english, middle pitch or mid-range pacing. Match their preferences; narration is not limited to low voices."},"status":"live"},{"id":"af_bella","name":"Bella","language":"en-US","accent":"American English","sample_url":"/v1/audio/voices/af_bella/sample","description":"American English. Natural, friendly general-assistant delivery. Measured higher pitch and mid-range pace relative to these seven voices at normal speed.","listening_assessment":{"reviewed_at":"2026-09-09","reviewer":"service_owner","basis":"Human listening assessment of supplied synthetic voice samples","limitations":"Subjective assessment by one listener; delivery may change with text. Suggested uses are recommendations, not validated performance guarantees.","summary":"Natural, friendly general-assistant delivery.","naturalness":"natural","delivery_tags":["friendly","general_assistant"],"suggested_uses":["narration","general_use","assistant_responses"]},"acoustics":{"pitch_median_hz":204.8,"pitch_p10_hz":170.6,"pitch_p90_hz":253.5,"pitch_variation_semitones":6.9,"estimated_wpm":184.0,"passage_median_pitch_hz_range":[202.1,209.6],"passage_wpm_range":[160.9,217.4]},"relative_tags":{"comparison_group":"catalogue-7-at-speed-1","pitch":"higher","pace":"mid-range","pitch_variation":"lower"},"subjective_traits":{"warmth":null,"mood":null,"perceived_age":null,"status":"Warmth, mood and age not rated; human delivery descriptions are in listening_assessment"},"emotion_control":false,"selection_guidance":{"basis":"conditional heuristic, not a validated suitability rating","human_suggested_uses":["narration","general_use","assistant_responses"],"human_delivery_tags":["friendly","general_assistant"],"text":"Consider when a caller requests american english, higher pitch or mid-range pacing. Match their preferences; narration is not limited to low voices."},"status":"live"},{"id":"bf_emma","name":"Emma","language":"en-GB","accent":"British English","sample_url":"/v1/audio/voices/bf_emma/sample","description":"British English. Natural, flat and informative delivery. Measured middle pitch and faster pace relative to these seven voices at normal speed.","listening_assessment":{"reviewed_at":"2026-09-09","reviewer":"service_owner","basis":"Human listening assessment of supplied synthetic voice samples","limitations":"Subjective assessment by one listener; delivery may change with text. Suggested uses are recommendations, not validated performance guarantees.","summary":"Natural, flat and informative delivery.","naturalness":"natural","delivery_tags":["flat","informative"],"suggested_uses":["narration","general_use"]},"acoustics":{"pitch_median_hz":180.3,"pitch_p10_hz":154.9,"pitch_p90_hz":214.0,"pitch_variation_semitones":5.6,"estimated_wpm":206.8,"passage_median_pitch_hz_range":[179.8,180.7],"passage_wpm_range":[176.6,240.8]},"relative_tags":{"comparison_group":"catalogue-7-at-speed-1","pitch":"middle","pace":"faster","pitch_variation":"lower"},"subjective_traits":{"warmth":null,"mood":null,"perceived_age":null,"status":"Warmth, mood and age not rated; human delivery descriptions are in listening_assessment"},"emotion_control":false,"selection_guidance":{"basis":"conditional heuristic, not a validated suitability rating","human_suggested_uses":["narration","general_use"],"human_delivery_tags":["flat","informative"],"text":"Consider when a caller requests british english, middle pitch or faster pacing. Match their preferences; narration is not limited to low voices."},"status":"live"},{"id":"bf_alice","name":"Alice","language":"en-GB","accent":"British English","sample_url":"/v1/audio/voices/bf_alice/sample","description":"British English. Natural, informative newsreader-style delivery. Measured higher pitch and faster pace relative to these seven voices at normal speed.","listening_assessment":{"reviewed_at":"2026-09-09","reviewer":"service_owner","basis":"Human listening assessment of supplied synthetic voice samples","limitations":"Subjective assessment by one listener; delivery may change with text. Suggested uses are recommendations, not validated performance guarantees.","summary":"Natural, informative newsreader-style delivery.","naturalness":"natural","delivery_tags":["informative","newsreader"],"suggested_uses":["narration","general_use","news_reading"]},"acoustics":{"pitch_median_hz":202.3,"pitch_p10_hz":153.9,"pitch_p90_hz":272.1,"pitch_variation_semitones":9.9,"estimated_wpm":206.6,"passage_median_pitch_hz_range":[201.4,204.6],"passage_wpm_range":[176.8,245.9]},"relative_tags":{"comparison_group":"catalogue-7-at-speed-1","pitch":"higher","pace":"faster","pitch_variation":"higher"},"subjective_traits":{"warmth":null,"mood":null,"perceived_age":null,"status":"Warmth, mood and age not rated; human delivery descriptions are in listening_assessment"},"emotion_control":false,"selection_guidance":{"basis":"conditional heuristic, not a validated suitability rating","human_suggested_uses":["narration","general_use","news_reading"],"human_delivery_tags":["informative","newsreader"],"text":"Consider when a caller requests british english, higher pitch or faster pacing. Match their preferences; narration is not limited to low voices."},"status":"live"},{"id":"bm_george","name":"George","language":"en-GB","accent":"British English","sample_url":"/v1/audio/voices/bm_george/sample","description":"British English. Natural, informative and soft delivery. Measured lower pitch and mid-range pace relative to these seven voices at normal speed.","listening_assessment":{"reviewed_at":"2026-09-09","reviewer":"service_owner","basis":"Human listening assessment of supplied synthetic voice samples","limitations":"Subjective assessment by one listener; delivery may change with text. Suggested uses are recommendations, not validated performance guarantees.","summary":"Natural, informative and soft delivery.","naturalness":"natural","delivery_tags":["informative","soft"],"suggested_uses":["narration","general_use"]},"acoustics":{"pitch_median_hz":137.7,"pitch_p10_hz":109.7,"pitch_p90_hz":167.9,"pitch_variation_semitones":7.4,"estimated_wpm":180.1,"passage_median_pitch_hz_range":[136.3,138.7],"passage_wpm_range":[155.2,215.2]},"relative_tags":{"comparison_group":"catalogue-7-at-speed-1","pitch":"lower","pace":"mid-range","pitch_variation":"middle"},"subjective_traits":{"warmth":null,"mood":null,"perceived_age":null,"status":"Warmth, mood and age not rated; human delivery descriptions are in listening_assessment"},"emotion_control":false,"selection_guidance":{"basis":"conditional heuristic, not a validated suitability rating","human_suggested_uses":["narration","general_use"],"human_delivery_tags":["informative","soft"],"text":"Consider when a caller requests british english, lower pitch or mid-range pacing. Match their preferences; narration is not limited to low voices."},"status":"live"},{"id":"am_michael","name":"Michael","language":"en-US","accent":"American English","sample_url":"/v1/audio/voices/am_michael/sample","description":"American English. Natural, informative and soothing delivery. Measured lower pitch and slower pace relative to these seven voices at normal speed.","listening_assessment":{"reviewed_at":"2026-09-09","reviewer":"service_owner","basis":"Human listening assessment of supplied synthetic voice samples","limitations":"Subjective assessment by one listener; delivery may change with text. Suggested uses are recommendations, not validated performance guarantees.","summary":"Natural, informative and soothing delivery.","naturalness":"natural","delivery_tags":["informative","soothing"],"suggested_uses":["narration","general_use"]},"acoustics":{"pitch_median_hz":112.0,"pitch_p10_hz":91.8,"pitch_p90_hz":151.0,"pitch_variation_semitones":8.6,"estimated_wpm":171.5,"passage_median_pitch_hz_range":[110.7,114.0],"passage_wpm_range":[148.1,201.9]},"relative_tags":{"comparison_group":"catalogue-7-at-speed-1","pitch":"lower","pace":"slower","pitch_variation":"higher"},"subjective_traits":{"warmth":null,"mood":null,"perceived_age":null,"status":"Warmth, mood and age not rated; human delivery descriptions are in listening_assessment"},"emotion_control":false,"selection_guidance":{"basis":"conditional heuristic, not a validated suitability rating","human_suggested_uses":["narration","general_use"],"human_delivery_tags":["informative","soothing"],"text":"Consider when a caller requests american english, lower pitch or slower pacing. Match their preferences; narration is not limited to low voices."},"status":"live"},{"id":"am_fenrir","name":"Ben","language":"en-US","accent":"American English","sample_url":"/v1/audio/voices/am_fenrir/sample","description":"American English. Natural, friendly general-assistant delivery. Measured lower pitch and faster pace relative to these seven voices at normal speed.","listening_assessment":{"reviewed_at":"2026-09-09","reviewer":"service_owner","basis":"Human listening assessment of supplied synthetic voice samples","limitations":"Subjective assessment by one listener; delivery may change with text. Suggested uses are recommendations, not validated performance guarantees.","summary":"Natural, friendly general-assistant delivery.","naturalness":"natural","delivery_tags":["friendly","general_assistant"],"suggested_uses":["narration","general_use","assistant_responses"]},"acoustics":{"pitch_median_hz":134.4,"pitch_p10_hz":97.8,"pitch_p90_hz":193.4,"pitch_variation_semitones":11.8,"estimated_wpm":200.5,"passage_median_pitch_hz_range":[132.6,137.8],"passage_wpm_range":[178.8,231.1]},"relative_tags":{"comparison_group":"catalogue-7-at-speed-1","pitch":"lower","pace":"faster","pitch_variation":"higher"},"subjective_traits":{"warmth":null,"mood":null,"perceived_age":null,"status":"Warmth, mood and age not rated; human delivery descriptions are in listening_assessment"},"emotion_control":false,"selection_guidance":{"basis":"conditional heuristic, not a validated suitability rating","human_suggested_uses":["narration","general_use","assistant_responses"],"human_delivery_tags":["friendly","general_assistant"],"text":"Consider when a caller requests american english, lower pitch or faster pacing. Match their preferences; narration is not limited to low voices."},"status":"live"}],"service_status":"live","price_usdc":"0.005","endpoint":"/v1/audio/speech","authentication":"x402 only; no account or reference approval","catalogue_version":"2026-09-10.2","query_price_usdc":"0","measurement_notes":"Pitch and pace are estimates across four sample passages per voice, including pauses. Delivery descriptions are the owner’s subjective listening assessment. Text can change delivery; no emotion controls are offered.","attribution":"Catalogue voices generated using Apache-2.0 licensed Kokoro weights by hexgrad. Names are service labels, not claims about real people. Publisher: https://huggingface.co/hexgrad/Kokoro-82M"}