I'm trying to work with my overseas vendor and they are not really providing a lot of information.

We are working on an educational toy that will give you facts and then asks questions.

We will have A LOT OF human speech and a handful of sound effects.

I'm trying to fit as much audio on the chip as possible.

What sampling rate should I use for voice? 11.025 KHz? 22.5 KHz? What sampling rate should I use for the sound effects? 22.5KHz?

The speaker is a 'cheap' toy speaker...not high fidelity.

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    \$\begingroup\$ Put some recording software on your PC and try it at various sample rates to get a feel for the quality. \$\endgroup\$ – Transistor Aug 30 '16 at 22:05
  • \$\begingroup\$ The ideal test is to play it back on the reference system. I can approximate it with software but it won't be ideal. \$\endgroup\$ – milesmeow Aug 30 '16 at 22:07
  • \$\begingroup\$ You probably need to at least provide details on the chip with link to datasheet. Otherwise we're going to guess (or close the question as being too broad or seeking opinion based answers). What quality do you want? \$\endgroup\$ – Transistor Aug 30 '16 at 22:10
  • \$\begingroup\$ Vendor is not forthcoming with that info. Will post it here as soon as I get it. :) \$\endgroup\$ – milesmeow Aug 30 '16 at 22:11
  • \$\begingroup\$ Consider compression scheme as part of your decision. For example, if the processor can handle MP3, for the same bit rate for most clips, it would be higher quality than telephony u/A-law and much higher quality than uncompressed linear PCM. \$\endgroup\$ – rioraxe Aug 31 '16 at 20:29

If telephone quality is adequate, then use that technology.

There is a lot of information on the www about digital telephone signals. For example Wikipedia: Pulse-code modulation 'Demodulation' explains:

For example, in telephony, the usable voice frequency band ranges from approximately 300 Hz to 3400 Hz.

and goes on to say:

Therefore, per the Nyquist–Shannon sampling theorem, the sampling frequency (8 kHz) must be at least twice the voice frequency (4 kHz) for effective reconstruction of the voice signal.

Telephone signals use a data rate of 64kbit/s. It is not a linear signal encoding, unlike CD.

Try the sound effects at exactly the same rate for simplicity.

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