wav
31.3 KBLoudness Ladder: Silent (440 Hz)
1 s 440 Hz tone at linear amplitude 0.0 (digital silence): rung on the Wave E loudness ladder.
- File
- WAV · Loudness Ladder · 1 s
- Use case
- Loudness / LUFSAudio analysis· Conversion set
Explore the test library
Find files, editable templates and browser test targets by what you need to make or test. The directory below is cut by format; the two collections under it cut the same library by subject and by workflow.
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wav
31.3 KBLoudness Ladder: Very Loud (440 Hz)
1 s 440 Hz tone at linear amplitude 0.75 (~-2.5 dBFS peak): rung on the Wave E loudness ladder.
- File
- WAV · Loudness Ladder · 1 s
- Use case
- Loudness / LUFSAudio analysis· Conversion set
wav
31.3 KBLoudness Ladder: Very Quiet (440 Hz)
1 s 440 Hz tone at linear amplitude 0.02 (~-34.0 dBFS peak): rung on the Wave E loudness ladder.
- File
- WAV · Loudness Ladder · 1 s
- Use case
- Loudness / LUFSAudio analysis· Conversion set
m4a
72.3 KBM4A: AAC (MP4)
The clip as AAC in an MP4/M4A container (faststart): Apple's default audio container. For testing M4A parsing and MP4 audio conversion.
- File
- M4A · Codec Set · AAC-LC
- Use case
- Conversion testingAudio analysis· Conversion set
m4r
72.3 KBM4R: iPhone Ringtone
The clip as an M4R iPhone ringtone: AAC in an MP4 container with the ringtone extension. For testing that a converter maps M4R↔M4A correctly.
- File
- M4R · Codec Set · AAC-LC
- Use case
- Conversion testingAudio analysis· Conversion set
wav
172.3 KBMelody: C Major Scale (WAV)
A two-second melody playing an ascending C-major scale (C4 to C5) with per-note envelopes: a simple musical signal for testing pitch detection, onset detection, and playback.
- File
- WAV · Signals · 2 s
- Use case
- Audio analysis
wav
39.2 KBMenu narration: chain telephone
A 5 second excerpt of this group's take, telephone chain. Band-limited, resampled and companded in one pass: the whole telephone path applied at once rather than one effect at a time. Delivered as pcm_mulaw at 8000 Hz mono. Scored against plate.flac in the same group, which is the same five seconds undamaged. The parameters in the specification are what the file MEASURED, not what was requested of it.
- File
- WAV · Speech Ladders · pcm_mulaw
- Use case
- ASR testingAudio analysis+1· Conversion set
flac
148.1 KBMenu narration: clipped
A 5 second excerpt of this group's take, clipping. Samples driven past a fixed threshold and flattened, the damage a hot microphone does and the one no codec can undo. Delivered as flac at 24000 Hz mono. Scored against plate.flac in the same group, which is the same five seconds undamaged. The parameters in the specification are what the file MEASURED, not what was requested of it.
- File
- FLAC · Speech Ladders · flac
- Use case
- ASR testingAudio analysis+1· Conversion set
wav
39.2 KBMenu narration: codec g722 16k
A 5 second excerpt of this group's take, codec. Encoded and decoded through a real speech codec, so the artefacts are the ones the format actually produces rather than a simulation of them. Delivered as adpcm_g722 at 16000 Hz mono. Scored against plate.flac in the same group, which is the same five seconds undamaged. The parameters in the specification are what the file MEASURED, not what was requested of it.
- File
- WAV · Speech Ladders · adpcm_g722
- Use case
- ASR testingAudio analysis+1· Conversion set
gsm
8.1 KBMenu narration: codec gsm 8k
A 5 second excerpt of this group's take, codec. Encoded and decoded through a real speech codec, so the artefacts are the ones the format actually produces rather than a simulation of them. Delivered as gsm at 8000 Hz mono. Scored against plate.flac in the same group, which is the same five seconds undamaged. The parameters in the specification are what the file MEASURED, not what was requested of it.
- File
- GSM · Speech Ladders · gsm
- Use case
- ASR testingAudio analysis+1· Conversion set
mp3
79.5 KBMenu narration: codec mp3 128
A 5 second excerpt of this group's take, codec. Encoded and decoded through a real speech codec, so the artefacts are the ones the format actually produces rather than a simulation of them. Delivered as mp3 at 24000 Hz mono. Scored against plate.flac in the same group, which is the same five seconds undamaged. The parameters in the specification are what the file MEASURED, not what was requested of it.
- File
- MP3 · Speech Ladders · mp3
- Use case
- ASR testingAudio analysis+1· Conversion set
mp3
20 KBMenu narration: codec mp3 32
A 5 second excerpt of this group's take, codec. Encoded and decoded through a real speech codec, so the artefacts are the ones the format actually produces rather than a simulation of them. Delivered as mp3 at 24000 Hz mono. Scored against plate.flac in the same group, which is the same five seconds undamaged. The parameters in the specification are what the file MEASURED, not what was requested of it.
- File
- MP3 · Speech Ladders · mp3
- Use case
- ASR testingAudio analysis+1· Conversion set
wav
39.2 KBMenu narration: codec mulaw 8k
A 5 second excerpt of this group's take, codec. Encoded and decoded through a real speech codec, so the artefacts are the ones the format actually produces rather than a simulation of them. Delivered as pcm_mulaw at 8000 Hz mono. Scored against plate.flac in the same group, which is the same five seconds undamaged. The parameters in the specification are what the file MEASURED, not what was requested of it.
- File
- WAV · Speech Ladders · pcm_mulaw
- Use case
- ASR testingAudio analysis+1· Conversion set
opus
15.1 KBMenu narration: codec opus 24
A 5 second excerpt of this group's take, codec. Encoded and decoded through a real speech codec, so the artefacts are the ones the format actually produces rather than a simulation of them. Delivered as opus at 48000 Hz mono. Scored against plate.flac in the same group, which is the same five seconds undamaged. The parameters in the specification are what the file MEASURED, not what was requested of it.
- File
- OPUS · Speech Ladders · opus
- Use case
- ASR testingAudio analysis+1· Conversion set
flac
139.1 KBMenu narration: dropouts
A 5 second excerpt of this group's take, dropouts. Short spans silenced outright, as a packet-switched call drops them, so a transcriber must decide between a pause and a missing word. Delivered as flac at 24000 Hz mono. Scored against plate.flac in the same group, which is the same five seconds undamaged. The parameters in the specification are what the file MEASURED, not what was requested of it.
- File
- FLAC · Speech Ladders · flac
- Use case
- ASR testingAudio analysis+1· Conversion set
flac
425.9 KBMenu narration: full spoken take
The complete 15.6 second utterance at 24000 Hz mono FLAC, spoken by the af_bella voice at 0.95x rate. The five-second excerpt in this group's ladder is cut from this take, so anything needing real duration uses this file and anything comparing damage uses the ladder. Lossless, so it is the archival reference for the whole group.
- File
- FLAC · Speech Ladders · flac
- Use case
- ASR testingAudio analysis· Conversion set
flac
329.4 KBMenu narration: noise snr0
A 5 second excerpt of this group's take, noise. Broadband noise mixed in at a measured signal-to-noise ratio, which is where a denoiser is either working or not. Delivered as flac at 24000 Hz mono. Scored against plate.flac in the same group, which is the same five seconds undamaged. The parameters in the specification are what the file MEASURED, not what was requested of it.
- File
- FLAC · Speech Ladders · flac
- Use case
- ASR testingAudio analysis+1· Conversion set
flac
309.2 KBMenu narration: noise snr10
A 5 second excerpt of this group's take, noise. Broadband noise mixed in at a measured signal-to-noise ratio, which is where a denoiser is either working or not. Delivered as flac at 24000 Hz mono. Scored against plate.flac in the same group, which is the same five seconds undamaged. The parameters in the specification are what the file MEASURED, not what was requested of it.
- File
- FLAC · Speech Ladders · flac
- Use case
- ASR testingAudio analysis+1· Conversion set
flac
292.6 KBMenu narration: noise snr20
A 5 second excerpt of this group's take, noise. Broadband noise mixed in at a measured signal-to-noise ratio, which is where a denoiser is either working or not. Delivered as flac at 24000 Hz mono. Scored against plate.flac in the same group, which is the same five seconds undamaged. The parameters in the specification are what the file MEASURED, not what was requested of it.
- File
- FLAC · Speech Ladders · flac
- Use case
- ASR testingAudio analysis+1· Conversion set
flac
148.1 KBMenu narration: plate
A 5 second excerpt of this group's take, reference. The clean five-second excerpt every other file in this ladder is scored against. Delivered as flac at 24000 Hz mono. The parameters in the specification are what the file MEASURED, not what was requested of it.
- File
- FLAC · Speech Ladders · flac
- Use case
- ASR testingAudio analysis+1· Conversion set
flac
185.2 KBMenu narration: rate 16000
A 5 second excerpt of this group's take, resample. The same audio at a different sample rate, which is the step most speech pipelines get wrong silently by assuming their model's rate. Delivered as flac at 16000 Hz mono. Scored against plate.flac in the same group, which is the same five seconds undamaged. The parameters in the specification are what the file MEASURED, not what was requested of it.
- File
- FLAC · Speech Ladders · flac
- Use case
- ASR testingAudio analysis+1· Conversion set
flac
399.9 KBMenu narration: rate 44100
A 5 second excerpt of this group's take, resample. The same audio at a different sample rate, which is the step most speech pipelines get wrong silently by assuming their model's rate. Delivered as flac at 44100 Hz mono. Scored against plate.flac in the same group, which is the same five seconds undamaged. The parameters in the specification are what the file MEASURED, not what was requested of it.
- File
- FLAC · Speech Ladders · flac
- Use case
- ASR testingAudio analysis+1· Conversion set
flac
94.9 KBMenu narration: rate 8000
A 5 second excerpt of this group's take, resample. The same audio at a different sample rate, which is the step most speech pipelines get wrong silently by assuming their model's rate. Delivered as flac at 8000 Hz mono. Scored against plate.flac in the same group, which is the same five seconds undamaged. The parameters in the specification are what the file MEASURED, not what was requested of it.
- File
- FLAC · Speech Ladders · flac
- Use case
- ASR testingAudio analysis+1· Conversion set
txt
211 BMenu narration: recogniser transcript
What a speech recogniser returned for this take. It normalises: spoken "forty three dollars and eighteen cents" comes back as digits and a currency symbol. Compared with the reference script without normalising first, this disagrees on every number in the utterance and a word error rate computed that way reports a fault that does not exist. That gap is the point of the pair.
- File
- TXT · Speech Ladders
- Use case
- ASR testing· Paired fixture