[openal] Attenuation Roll-Off problems (too silent)

Roland Plüss roland at rptd.ch
Sun May 22 17:20:01 EDT 2022

So what settings would you use then? Increasing the volume or the 
reference distance? I have the impression increasing the reference 
distance leaves you with a sudden drop of volume out of the blue at the 
distance border.

Am 22.05.22 um 18:11 schrieb Chris Robinson:
> On Sunday, May 22, 2022 6:26:05 AM PDT Roland Plüss wrote:
>> Let's say I have a room of roughly 7x4m size. In the middle of the room
>> there is a sound source playing the sound of some kind of engine/motor
>> hence a looping, uniform sound. Since it is in the middle of the room
>> the sound source is 3.5m away from the door. The listener is located in
>> the door hence 3.5m away from the sound source. The volume of the source
>> is set to 1, reference distance to 1 and roll-off to 1. At the door the
>> sound is pretty much inaudible. That's what I got right now.
>> The sound file is normalized with peak gain at 0db. Audacity measures
>> the RMS as -13.74 db. This would be a mean volume of roughly 0.2.
>> Physically this would be 1/d = 0.2/3.5 = 0.057, hence roughly 6% volume.
>> This would explain why it is kinda inaudible at the door. Now what
>> values would you say are required to be used in OpenAL to make this
>> sound work? From the RMS value I would say the volume would need to be
>> scaled by 4.89 but OpenAL clamps this. If I use the attenuation rule 1/d
>> with 1=4.89/d then d=4.89 . Reference distance = 4.89?
> OpenAL clamps it after distance attenuation. If you set the gain to 4.89, it
> will first be calculated as 4.89 * (1/3.5) = 1.389, and that then gets
> clamped, so the final mix gain ends up being 1. Setting the reference distance
> will have the same effect: 1 * (4.89/3.5) = 1.389, which gets clamped to 1.
> The sound will play at full volume at that distance, regardless of which way
> you do it. The listener would have to move away by another 1.3 meters before
> the volume starts going down at the usual rate of half gain per doubling
> distance.
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