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| Codec | Male | Female |
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|---------------------|-------|--------|
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| Original | male | female |
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| Codec 2 3200 bit/s | male | female |
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| Codec 2 2400 bit/s | male | female |
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| Codec 2 1300 bit/s | male | female |
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| Codec 2 700C bit/s | male | female |
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Here is Codec 2 operating at 2400 bit/s compared to some other low bit rate codecs:
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| Codec | Male | Female |
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|---------------------|-------|--------|
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| Original | male | female |
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| Codec 2 2400 bit/s | male | female |
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| MELPe 2400 bit/s | male | female |
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| AMBE 2000 bit/s | male | female |
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| LPC-10 2400 bit/s | male | female |
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Notes: *Thank you very much Armin for providing the MELPe samples. The AMBE samples were generated using a [DV-Dongle](http://www.dvdongle.com/), a USB device containing the DVSI AMBE2000 chip. The LPC-10 samples were generated using the [Spandsp](http://www.soft-switch.org/) library.*
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Here is Codec 2 operating at 700 bit/s compared to MELPe at 600 bit/s:
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| Codec | Male | Female |
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|--------------------|-------|--------|
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| Original | male | female |
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| Codec 2 700 bit/s | male | female |
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| MELPe 600 bit/s | male | female |
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Here is Codec 2 operating at 3200 bit/s compared to some higher bit rate CELP codecs, typically used for VOIP and mobile phone work:
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| Codec | Male | Female |
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|---------------------|-------|--------|
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| Original | [male](http://www.rowetel.com/downloads/codec2/hts1a.wav) | [female](http://www.rowetel.com/downloads/codec2/hts2a.wav) |
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| Codec 2 3200 bit/s | [male](http://www.rowetel.com/downloads/codec2/hts1a_3200.wav) | [female](http://www.rowetel.com/downloads/codec2/hts2a_3200.wav) |
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| AMR 4750 bit/s | [male](http://www.rowetel.com/downloads/codec2/hts1a_amr475.wav) | [female](http://www.rowetel.com/downloads/codec2/hts2a_amr475.wav) |
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| g.729a 8000 bit/s | [male](http://www.rowetel.com/downloads/codec2/hts1a_g729a.wav) | [female](http://www.rowetel.com/downloads/codec2/hts2a_g729a.wav) |
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Here are some samples with acoustic background noise, similar to what would be experienced when driving a truck. As you can see (well, hear) background noise is a tough test for low bit rate vocoders. They achieve high compression rates by being highly optimised for human speech, at the expense of performance with non-speech signals like background noise and music. Note that Codec 2 has just one voicing bit, unlike mixed excitation algorithms like AMBE and MELP. The MELPe sample has the noise supression option enabled.
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| Codec | Male with truck noise |
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|---------------------|-----------------------|
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| Original | [male](http://www.rowetel.com/downloads/codec2/mmt1.wav) |
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| Codec 2 2400 bit/s | [male](http://www.rowetel.com/downloads/codec2/mmt1_2400.wav) |
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| AMBE 2000 bit/s | [male](http://www.rowetel.com/downloads/codec2/mmt1_AMBE2000.wav) |
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| MELPe 2400 bit/s | [male](http://www.rowetel.com/downloads/codec2/mmt1_melpe_2400.wav) |
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| LPC-10 2400 bit/s | [male](http://www.rowetel.com/downloads/codec2/mmt1_lpc10.wav) | |
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\ No newline at end of file |
