Easy Question on loudness

[jerseydevil]

Easy Question. What is the purpose of the loudness button on stereos? Why not just increase the volume?

[Daddy Dee]

The purpose is to enhance the sound at lower listening levels.

Simply boosts bass and treble frequencies, which need boost to sound full at lower db levels.

[dragonfyr]

Easy Question. What is the purpose of the loudness button on stereos? Why not just increase the volume?

Hey! Where does this guy get off using (un)common sense!?

...And forego the pleasure of tone controls (EQ)!!!

I can see now that you're not going to last long around here![][]

[michael hurd]

Humans do not hear low frequencies very well, until the overall volume level is higher, then we hear them at a level that is closer to that of midrange.

The loudness button boosts the bass and treble, and we can hear a more balanced ( to our ears ) sound, at lower listening levels.

Usually this is used for conversational levels of music, rather than at higher volumes.

[DrWho]

Do a search on Fletcher-Munson Equal Loudness curves and you will

probably find your answer there - The music recorded onto the CD was

probably mixed in the 90dB region which is where the human ear is the

flattest. If you come home and listen at 70dB, you will notice on the

F-M curves that certain frequencies need to be a lot louder in order to

be percieved to be the same volume. I'm on a computer in a lab

right now so I don't have my charts, so let's pretend that a sound

centered around 80Hz needs to be 15dB louder at 70dB than it does at

90dB (keep in mind that this is relative to the rest of the frequency

spectrum). What your loudness button will do is implement a 15dB boost

at 80Hz so that the overall balance of the mix is the same as the

balance when it was recorded in the studio at 90dB. The same thing

happens at the other end of the spectrum with the high frequencies, but

you will notice the magnitude of change isn't as large (so we usually

notice a bigger difference in the low frequency output when we push the

button).

Some really fancy pre-amps and amplifiers actually implement a loudness

curve that changes with the volume dial (which involves a little

calibration thanks to differing speaker sensitivities and all that). It

is hard to tell someone when they should push the button (which is

going to be a preset EQ that doesn't change) so you're best off setting

the loudness to whatever sounds best to you (afterall, your personal

entertainment is the end goal).

Anyways, I hope all this made sense. If not go find some charts online

and hopefully it will become more clear. A lot of them provide fancy

descriptions as well (which are prob better than mine) []

[michael hurd]

Reference this picture of the range of sound, and how linear we hear, you will see that we definately do not hear low frequencies well.

This chart is called a Fletcher-Munson equal loudness countour.

[pauln]

The appearance of the "loudness" on amps is as silly as it gets. Low level music sounds the way it sounds because it is supposed to sound like that. Boosted bass and treble is not appropriate for low level listening and will sound un-natural. It might be observed that if you are wanting to reproduce music accurately, let the bass and treble stay low the way it is in nature and your ear.

Some say we definately do not hear low frequencies well - but this is based on he incorrect assumption that all the frequency levels at low levels should be like when at high levels. There is nothing wrong with the way your ears hear frequencies differently at different levels - this is the way it is supposed to be.

Others might say that at louder and louder levels, we don't hear the midrange frequencies as well.

Paul

[DrWho]

Others might say that at louder and louder levels, we don't hear the midrange frequencies as well.

You're not reading the graph correctly then if you make that claim...Now I know the graph is calibrated at 1kHz, but that doesn't change the fact that the ear is a lot more linear (well technically logorithmic) in the 1kHz region than it is with the low frequencies.

For example, when going from a loudness of 50dB to 60dB a 1kHz signal also increases by 10dB SPL. However, the equivalent loudness low frequency of 30Hz goes from 83dB to 85dB (aka, a 10dB increase in loudness corresponds to a 2dB change in SPL). When going from 100dB to 110dB, both 1kHz and 30Hz are now both increasing by 10dB as well, but the 30Hz still needs to be 3dB louder to be percieved as the same volume. What we see here is that our ears are very inaccurate with low frequencies - Note that on the other end of the scale that the high frequencies are almost as 'linear' as the midrange, though they just need to be bumped up 10dB. In other words, a 10dB increase in SPL still corresponds to a 10dB increase in apparent loudness. This is why we say that we don't hear low frequencies very well and is also why we calibrate to 1kHz (because 10dB in loudness corresponds to 10dB in SPL).

Anyways, I would have to greatly disagree with the sentiment that music sounds better without loudness compensation for the sole reason that we aren't listening to a single perfectly recorded sound. About 50% of the enjoyment in music comes from the lower end of the spectrum, and if for whatever reason I must listen at 70dB then I'm certainly not going to sit there and miss out on over half of the music. Even with the most perfect recording of a symphony orchestra - there are low frequency sounds that one would miss out on if listening at 70dB. Noboy likes sitting a mile away from the orchestra during a live show and I'm certainly not going to enjoy that sound in my home either.

To think of it another way, what if the mixer in the studio recorded our symphony at 70dB? And then we come home and listen to this recording at 90dB (which is the linear reference range ) - the bass is simply going to be insanely overpowering, but this is how it is "supposed to be because that's the way the loudness function works." That's just crap logic if you ask me. You can tell that some of the old classic rock and roll was recorded at like 110dB in the studio because when you come home and listen at 85dB, there is simply no bass at all. Loudness control is simply a function that gives the listener the ability to bring the reference point down to the preferred listening level. A loudness button is either on or off, but that is why I mentioned the variable calibrated controls that do exist out there, and which sound far from unnatural.

I suppose I could listen to a crappy LP and conclude that LP's suck and that I shouldn't try anything to improve the sound because altering the signal path for my own enjoyment is "wrong" and I should just live with "the way it is", even if it means less enjoyment. Crap, here I thought our systems were for enjoyment - not for accurate playback. Silly me, I suppose the enjoyment systems belong in the studio then.

[Spkrdctr]

Catfight!

[PrestonTom]

This issue of the "loudness" knob comes up periodically. And when one looks at the logic of it, in fact it does not make sense given a certain assumption.

Stereo reproduction at a low level will (and should not) not have much perceived bass. Live music at a low level (perhaps at a great distance etc) will also not have much preceived bass. The assumption (and one that I subscribe to) is that the the goal of the reproduction is accuracy. In simple words, does it sound like the real thing or can I close my eyes and get a sense of "being there". There is no "volume" knob (or bass enahncement) in the real world. The Fletcher-Munson curves are real. The bass is not very "loud" at low levels, why should it be so on our stereo in the living room?

Paul is absolutely correct given the above assumption about the goal of accuracy. I agree with him. I will confess; however, that on occassion when I can not turn up the level I will resort to a "loudness" knob.

Good Luck,

-Tom

[Duke Spinner]

your Ear ......

is a Mechanical Device ....well, mostly

it is a Lever,hooked to a Diaphram

if you look at the mechanical engineering aspect's of it's operation....

you can define the non-linearity of the mechanical advantage present in the "lever"

[homemade]

I always enjoyed using the loudness control on my old JVC reciever but Yamaha no longer employs it and I'm pretty sure most other receivers don't have it now either. What a perfect way to get some bass from the bass shy Klipsch Heritage speakers. The only problem is that the efficiency is so high on these models that the built-in loudness compensation ends up boosting too much at the higher volumes. Most loudness controls were designed to have no effect once the volume passes the half way point but my homebuilt khorns seldom need volume above the 1/4th way and 1/2 way up I'm looking at 120db in the middle of the room with a 60watt amp!

[homemade]

BTW: Zenith produced stereoes in the late 70's that had nondefeatable loudness controls. My brother sold his Zenith "wedge" to a friend and I sold the friend some speakers I had (12inch alnico woofers that went flat to 30hz in a big ported enclosure) and were fairly efficient and the bass these put out were great with just 12 watts per channel. I've got one of these "wedges" for our shop and some day will hook it up when the old admiral stereo gives up. If anyone remembers these "wedges"-it was one of the first major electronics companies that started to produce a decent stereo setup. This one had a built-in 8 track recorder (possible with dolby-can't remember for sure), tuner knob that had some flywheel effect and decent 10inch ported speakers. Didn't sound bad compared to the other store bought all in one units at that time.

[fletcherkane]

My brand new Pioneer 1015tx has a "Loudness" control. It actually has two settings. Midnight Listening, and Loudness. Loudness does just what has been discussed above, and Midnight compresses the loud and soft parts of a movie sound track so that you aren't constantly turning the volume up and down while listening to movies when others in your house are trying to sleep....

[mikebse2a3]

This issue of the "loudness" knob comes up periodically. And when one looks at the logic of it, in fact it does not make sense given a certain assumption.

Stereo reproduction at a low level will (and should not) not have much perceived bass. Live music at a low level (perhaps at a great distance etc) will also not have much preceived bass. The assumption (and one that I subscribe to) is that the the goal of the reproduction is accuracy. In simple words, does it sound like the real thing or can I close my eyes and get a sense of "being there". There is no "volume" knob (or bass enahncement) in the real world. The Fletcher-Munson curves are real. The bass is not very "loud" at low levels, why should it be so on our stereo in the living room?

Paul is absolutely correct given the above assumption about the goal of accuracy. I agree with him. I will confess; however, that on occassion when I can not turn up the level I will resort to a "loudness" knob.

Good Luck,

-Tom

If you look at this subject of accuracy deeper then we need to realize a few things:

No Human Voice or Instrument comes from two or more locations(ie:speakers) so their is nothing natural abought how we record or playback music now or how we listen to it. We have just been tricking our ear/brain for an illusion of reality.

If a Band is recorded at realistic live levels then it seems to me the only way we will maintain that Tonal Balance is to playback at those live levels and any other level is going to shift things Tonally. So if where you listen won't allow those levels of reproduction the best you can do to create the illusion is to alter your tonal balance to sound as natural as possible in any given situation and for recordings(which vary all over the place).

My personal Goal and Point is GO FOR REALISM of your Music in your own situation the best you can. You should feel free to use the tools we have now whether it is Loudness Controls, Equalizers, Surround Sound and Etc... to acheive this goal of realism in our own situations. I see nothing very accurate about the method of how we reproduce Music at the present time. If we accept the inaccuracy of using two speakers to reproduce the illusion of a central image(NOTHING REAL IN NATURE HERE) then how is it any more inaccurate to use Loudness Controls and other Methods to acheive Realism in Reproduction?

Enjoy Your Music!!!!

mike[]

[colterphoto1]

I always enjoyed using the loudness control on my old JVC reciever but Yamaha no longer employs it and I'm pretty sure most other receivers don't have it now either. What a perfect way to get some bass from the bass shy Klipsch Heritage speakers. The only problem is that the efficiency is so high on these models that the built-in loudness compensation ends up boosting too much at the higher volumes. Most loudness controls were designed to have no effect once the volume passes the half way point but my homebuilt khorns seldom need volume above the 1/4th way and 1/2 way up I'm looking at 120db in the middle of the room with a 60watt amp!

Yamaha 2 ch receivers still have the variable loudness control. My RX 596 sports it and I like the control it allows. This is my home office unit so it's generally low level listening but I prefer to be able to dial in the adjustment for the given volume.

This unit is still available and sports 80x2 watts, damping factor of 240, phono inputs and separate record out. I think it's a very nice moderately priced modern stereo receiver.

Michael

[Hardhead]

For goodness sake, don't let pauln find out about RIAA equalization or any of the several noise reduction circuits! They ain't natural!

[WMcD]

I believe that many loudness contols only effect the bass, even though, as pointed out, the treble should be boosted too. One design published a long time ago does just that. I wonder what the Yammie system does.

One article I read long ago pointed out something interesting which can be inferred from the F-M curves. You see that the lower the level in the midrange, the more boost that is necessary.

You could almost set the level of low bass to th 90 or 100 dB level and leave it there, then decrease the midrange. Of course that doesn't work out across the board. It does, though show how bad the situation is!

Gil

[colterphoto1]

I looked up the Yamaha Loudness control and was surprised. Instead of claiming +Xdb and LFhz and +Ydb at HFhz, it gave a 'up to -30db at 1kHz' spec. That would seem to make it a midrange reduction-only control, unless they've just got it worded in a screwy fashion.

I'm going to contact them to see what their circuit does. Good question.

Michael

[WMcD]

Mike,

I think you might be on to something and took my idea further than I did. We could look at loudness compensation as just being midrange attenuation, leaving the bass and treble at some reference.

My observations came from the ancient days of analog circuits. Now with DSP, just about anything can be done. It is just difficult to figure out what is being done.

My old cheap Sony DVD player has an audio setting for "night". It is to be used so as not to disturb the other members of the household and the neighboors, while still giving good listening. HT receivers sometimes have such settings.

I suspect it is loudness and compression.

Gil