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Audio quality comparisons

April 25, 2019 · By James Cridland · 2.9 minutes to read

What effect does bitrate, samplerate, and mono/stereo have on audio quality?

Here are a set of pieces of audio to help find out, as an apples-to-apples comparison. They’re all authored for -16 LUFS, since the loudness of something affects our perception of its quality. They’re from our daily podcast, which you can subscribe to on your favourite podcast player.

If you want to find out what people are actually using, we’ve analysed hundreds of podcasts.

The original

Almost the original file. This system records at 44.1kHz, so I’ve used that here: a 48kHz file would be even larger. I’ve applied loudness correction to make it the same loudness as the other files here (-16 LUFS).

1,400kbps, 44.1kHz, stereo, wav: (33.7MB)

At 160kbps

If I was authoring a stereo podcast, I’d use this.

160kbps, 44.1kHz, stereo, mp3: (3.9MB)

At 64kbps

All these files are the same size, but encoded in different ways. Listen to the sibilant sounds (the 's’ sound in the word “podcast”, for example). Most listeners to Podnews will hear it at 64kbps 44.1kHz AAC-HE.

64kbps, 22.05kHz, mono, mp3: (1.6MB)

64kbps, 48kHz, mono, mp3: (1.6MB)

64kbps, 48kHz, stereo, mp3: (1.6MB)

64kbps, 48kHz, stereo, AAC-HE: (1.5MB)

At lower bitrates

Here’s 24kbps. This is a significantly lower bitrate, but still offers quite good sound quality in mono AAC-HE.

24kbps, 22.05kHz, mono, mp3: (600KB)

24kbps, 22.05kHz, mono, AAC-HE: (600KB)

24kbps, 22.05kHz, stereo, AAC-HE: (600KB)

24kbps, 48kHz, stereo, AAC-HE: (600KB)

At a really low bitrate

You’d not use this for anything, but it’s worthwhile listening to the audio quality comparison between the top two. Also, worth listening to how much muddier the sound begins to sound if we use 48kHz sampling rather than 16kHz sampling here. AAC-HE won’t even let you choose stereo for this bitrate, though MP3 will: listen to find out why this is a bad idea.

16kbps, 16kHz, mono, mp3: (410KB)

16kbps, 22.05kHz, stereo, mp3: (410KB)

16kbps, 16kHz, mono, AAC-HE: (410KB)

16kbps, 22.05kHz, mono, AAC-HE: (410KB)

16kbps, 48kHz, mono, AAC-HE: (410KB)

And being very silly

Mmm, my.

8kbps, 8kHz, stereo, mp3: (257KB)

—James is the Editor of Podnews, and was first involved in podcasting in January 2005.

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