FreeCalypso > hg > freecalypso-docs
annotate Audio-tone-amplitudes @ 108:e26623146358 default tip
new article DSP-speech-decoder
author | Mychaela Falconia <falcon@freecalypso.org> |
---|---|
date | Tue, 29 Oct 2024 22:11:41 +0000 |
parents | 8ce3bd7c0164 |
children |
rev | line source |
---|---|
80
8ce3bd7c0164
Audio-tone-amplitudes article written
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff
changeset
|
1 In our current Luna development setup, we use a wired headset (currently |
8ce3bd7c0164
Audio-tone-amplitudes article written
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff
changeset
|
2 FC-HDS4, previously iWOW's) as our primary audio device, connected to Iota EAR |
8ce3bd7c0164
Audio-tone-amplitudes article written
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff
changeset
|
3 output, and the same arrangement will be used on FC Venus, our planned successor |
8ce3bd7c0164
Audio-tone-amplitudes article written
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff
changeset
|
4 to FC Luna. The gist of the situation is that the firmware "thinks" that we are |
8ce3bd7c0164
Audio-tone-amplitudes article written
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff
changeset
|
5 in the classic handheld setup, but in reality it is a headset inserted into the |
8ce3bd7c0164
Audio-tone-amplitudes article written
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff
changeset
|
6 developer-operator's ear canal. |
8ce3bd7c0164
Audio-tone-amplitudes article written
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff
changeset
|
7 |
8ce3bd7c0164
Audio-tone-amplitudes article written
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff
changeset
|
8 The amplitudes of various audio tones emitted by the firmware through the DSP |
8ce3bd7c0164
Audio-tone-amplitudes article written
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff
changeset
|
9 need to be adjusted for this in-ear headset reality, in order to provide |
8ce3bd7c0164
Audio-tone-amplitudes article written
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff
changeset
|
10 reasonable ear comfort to the developer-operator and to prevent hearing damage. |
8ce3bd7c0164
Audio-tone-amplitudes article written
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff
changeset
|
11 The "classic" amplitudes for fw-generated audio tones (-7 to -5 dBfs) make sense |
8ce3bd7c0164
Audio-tone-amplitudes article written
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff
changeset
|
12 for a true phone handset with a 32 ohm earpiece speaker, and furthermore, these |
8ce3bd7c0164
Audio-tone-amplitudes article written
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff
changeset
|
13 "classic" tone amplitudes are only appropriate when the tones are generated |
8ce3bd7c0164
Audio-tone-amplitudes article written
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff
changeset
|
14 while the user holds the phone away from her ear - otherwise they are too loud. |
8ce3bd7c0164
Audio-tone-amplitudes article written
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff
changeset
|
15 But in our use case where an FC-HDS4 headset stays in the developer-operator's |
8ce3bd7c0164
Audio-tone-amplitudes article written
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff
changeset
|
16 ear canal for an entire work session, we need much lower tone amplitudes. |
8ce3bd7c0164
Audio-tone-amplitudes article written
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff
changeset
|
17 |
8ce3bd7c0164
Audio-tone-amplitudes article written
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff
changeset
|
18 Basic keybeep: the empirically found amplitude for operator comfort is -26 dBfs |
8ce3bd7c0164
Audio-tone-amplitudes article written
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff
changeset
|
19 for each of the two single tones. |
8ce3bd7c0164
Audio-tone-amplitudes article written
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff
changeset
|
20 |
8ce3bd7c0164
Audio-tone-amplitudes article written
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff
changeset
|
21 DTMF keybeep: the empirically found amplitude for operator comfort is -29 dBfs |
8ce3bd7c0164
Audio-tone-amplitudes article written
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff
changeset
|
22 for the low tone and -27 dBfs for the high tone. |
8ce3bd7c0164
Audio-tone-amplitudes article written
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff
changeset
|
23 |
8ce3bd7c0164
Audio-tone-amplitudes article written
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff
changeset
|
24 Approximately good amplitudes for the remaining tones: |
8ce3bd7c0164
Audio-tone-amplitudes article written
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff
changeset
|
25 |
8ce3bd7c0164
Audio-tone-amplitudes article written
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff
changeset
|
26 Call waiting tone: -23 dBfs |
8ce3bd7c0164
Audio-tone-amplitudes article written
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff
changeset
|
27 Ringing tone: -28 dBfs |
8ce3bd7c0164
Audio-tone-amplitudes article written
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff
changeset
|
28 Radio acknowledge (currently unused): -26 dBfs |
8ce3bd7c0164
Audio-tone-amplitudes article written
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff
changeset
|
29 Busy/congestion/dropped: -27 dBfs |
8ce3bd7c0164
Audio-tone-amplitudes article written
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff
changeset
|
30 SIT error tone: -28 dBfs |
8ce3bd7c0164
Audio-tone-amplitudes article written
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff
changeset
|
31 |
8ce3bd7c0164
Audio-tone-amplitudes article written
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff
changeset
|
32 All of these dBfs numbers listed above should be regarded as starting points |
8ce3bd7c0164
Audio-tone-amplitudes article written
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff
changeset
|
33 for possible further tuning once we implement the necessary framework in our |
8ce3bd7c0164
Audio-tone-amplitudes article written
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff
changeset
|
34 firmware for generating audio tones at configurable amplitudes - and this |
8ce3bd7c0164
Audio-tone-amplitudes article written
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff
changeset
|
35 implementation most likely won't happen before FC Venus: Condat's entanglement |
8ce3bd7c0164
Audio-tone-amplitudes article written
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff
changeset
|
36 between audio tones and the buzzer needs to be detangled first, and that task |
8ce3bd7c0164
Audio-tone-amplitudes article written
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff
changeset
|
37 requires a platform with a working buzzer. |
8ce3bd7c0164
Audio-tone-amplitudes article written
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff
changeset
|
38 |
8ce3bd7c0164
Audio-tone-amplitudes article written
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff
changeset
|
39 With our present firmware, the only way to test different audio tone amplitudes |
8ce3bd7c0164
Audio-tone-amplitudes article written
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff
changeset
|
40 is via AT@TONE test command, which requires 16 numeric arguments. The high |
8ce3bd7c0164
Audio-tone-amplitudes article written
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff
changeset
|
41 effort of repeatedly composing these complex AT@TONE commands for each tested |
8ce3bd7c0164
Audio-tone-amplitudes article written
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff
changeset
|
42 amplitude of each tested tone creates fatigue, which then interferes with the |
8ce3bd7c0164
Audio-tone-amplitudes article written
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff
changeset
|
43 original objective of psychoacoustic testing of different amplitudes. |