[net.audio] Dynamic Range Estimate

rfg@hound.UUCP (08/09/83)

Let's assume your average acoustic suspension loudspeaker puts
out a sound pressure level of about 90db with a one watt input
(Some are louder, some not so loud. For high efficiency PA
speakers add 10-15 db.). Let's also assume the speaker can handle
100 watts of power. That brings us up to about 110db spl (120-125
for PA). OK, further assume it can handle short bursts of 200 watts -
add 3db, total 113 db spl (123-128 for PA).
At the other end, while the speaker can produce levels of sound as
low as you want to estimate, you won't hear them if they are below
the noise level of the listening location. Few listening locations are  
going to have background noise levels below 40db spl. In a car figure
at least 75-80db. Result: effective dynamic range of home type loud-
speakers is around 70 db, only 30-35 in moving car.
Add 3 db for two speakers (stereo) if you want to. You end up
at about the number for a disc (vinyl,lp) system and considerably
less than what CD is capable of. That does not mean that the CD
range is excessive and unnecessary - but that is another story.
                                   Dick Grantges HO-x4341

thomas@utah-gr.UUCP (Spencer W. Thomas) (08/10/83)

Speaking from experience using the Soundstream digital editing system
with Infinity speakers (I forget which model, they were the bit top of
the lines before the 25000$ ones came out), I will testify that you can
hear the entire 96db of dynamic range.  It was possible to hear the
one-bit "hash" you got at the end of a fade-out, and the speakers could
still handle the cannon shots (at the same volume setting) which peaked
out at very close to the top.  (It produced an amazing amount of cone
travel in the woofers).

In reference to another article, I would prefer to listen to the
Soundstream 16 bit system than the Magnavox(?) 14 bit.  A major failing of
linear encoding is that you have really BIG (relatively) quanta at very
low volume levels.  With a 14 bit encoding, this happens at 4 times
(12db) the volume level.

(The preceding has been my opinion.)

=Spencer

caf@cdi.UUCP (caf) (08/12/83)

Subtracting the ambient noise level of the listening room from the peak sound
level of a stereo system does not yield a valid figure for the perceptual
dynamic range of the setup for at least two reasons:

1.  The listener localizes sounds with binaural hearing.  The whirr of
an icebox in the next room can be distinguished from the program material/hiss
in much the same way that most people can pick out conversations in a cocktail
party.
2.  In addition to (1.), the ambient noise in the listening environment is
often in a different frequency rage from the music and/or hiss emanating
from the loudspeakers.

The last time I autitioned CD's was in a showroom with a rather noisy air
conditioner and indeed I couldn't hear any hiss on the CD's with risking
louspeaker armageddon.  However, at home, when things are quiet (with the
icebox off, etc.) I can sometimes hear the slight noise background from
digitally mastered DBX records cut in/out between selections.

When playing the best digitally encoded DBX records, the only "noise" I
really notice (aside from occaisional ticks and pops) is that made by
the conductor and orchestra in the process of playing the piece.
This makes the recording enjoyable and realistic to me.

As far as CD's for myself, I plan to hold off (and susbist on my collection
of DBX records) untill Pioneer introduces its combo LV/CD player.

-- 
Chuck Forsberg Computer Development Inc Portland OR cdi!caf (503)-646-1599

jeff@tesla.UUCP (Jeff Frey) (08/20/83)

Subjectively speaking, ambient noise IS important in listening to CDs.  WHen
I listen to a couple of mine, I like to turn off my refrigerator (in an adjacent
room).  I do live in a quiet area.
Has anyone ever heard a Japanese refrigerator?  Probably not, because they`re
hard to hear.  Probably about 6db less than an American model.  Now there`s
an appropriate subject for net.audio!
Jeff
PS  These opinions are not necessarily those of any any memo-generating 
bureaucrats at any or all telephone-related shrinking companies.

emrath@uiuccsb.UUCP (08/25/83)

#R:hound:-28600:uiuccsb:5700004:000:843
uiuccsb!emrath    Aug 25 01:53:00 1983

Wow, I think you hit on something.
I don't have a CD player, but I also get annoyed by refrigerator
noise at night, interfering with stereo listening. 
I don't want to turn it (the stereo vol) up such that I disturb
my neighbors or roommate, but when that heating ventilation system
kicks in I sometimes have to run over and crank it up a bit.
Then when it shuts off, the stereo seems rather loud.
Even the hum from the power transformers in my power amps
bothered me (i.e. I could hear it, not in the speakers mind you).
I'm probably crazy, but I went so far as to put cork pads between
the transformers and chassises (what IS the plural of chassis?).
It made a difference. (I suppose it would have been easier to set them
on a piece of carpet or something, but this was esthetically cleaner!)

During the day?  Turn it up & forget about it.