Measure's tone generator may go below what a XO's speakers can generate

[greenfeld]

Measure's tone generator for tuning instruments may go below what a XO can generate.

For example, the C3 (130.8 Hz) of a Viola cannot be generated on a XO-1.75 with the internal speakers regardless of volume level (it can be heard with external headphones). The G3 (196 Hz) can be heard with the internal speakers.

A D3 (146.8 Hz) can be barely heard suggesting we have a cutoff around 150 Hz.

We might be able to compensate by raising the generated volumes at lower frequencies as a "hearing aid" but I do not know how well this will work.

Heard in OLPC 13.1.0 os2.

[walter]

Good catch. In the Turtle Art example program that does something similar, I do make an adjustment for volume based as per your suggestion. There still seems to be a lower bound on the XO speakers. Will investigate how to best convey this to the user.

[greenfeld]

It might be worth asking the hardware team if they could give you an expected response/roll-off chart for each model.

The two different speaker designs for XO-4 may also have to be considered.