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MSM9836-xxx

¡ Semiconductor

3. Playback Method

This IC provides two kinds of playback methods, non-linear PCM algorithm and straight PCM

algorithm. When the 8-bit non-linear PCM algorithm is selected, sound quality can be improved

because a resolution equivalent to 10-bit straight PCM is available around the waveform center.

You can select either non-linear PCM algorithm or straight PCM algorithm for each phrase. Table

3.1 shows the relationship between playback methods and applicable sounds. It is recom-

mended to evaluate the sound quality before actual use.

Table 3.1 Relationship between playback methods and applicable sounds

The playback time is obtained by dividing the memory capacity by the bit rate.

The playback time for 8-bit PCM algorithm is obrained by using the following equation.

Memory capacity [bit]

Bit rate [bps]

Memory capacity [bit]

Sampling frequency [Hz] ¥ 8 [bit]

Playback time [sec] =

=

(3072–17) ¥ 1024 [bit]

8000 [Hz] ¥ 8 [bit]

Playback time =

= 48.8 [sec]

For example, if all phrases are stored in the MSM9836 at 8 kHz sampling frequency, the

maximum playback time is as follows.

Table 2.1 Maximum playback time

Playback method

Applicable sound

8-bit non-linear PCM algorithm Human voice

8-bit straight PCM algorithm

BEEP tone, sound effects

24.4

48.8

61.0

97.7

User's area

3055K bit

ROM capacity

3M bit

Maximum playback time (sec)

Model

MSM9836