Re: [Harp-L] Re: Combs

["Derwood Blues" <Derwood.Blues@xxxxxxxxx>]

My point about the siren was that the velocity of the siren, at least the
ones I have seen on firetrucks that spin, changes the frequency of the note
where on a harmonica the velocity does not effect the frequency, at least
within the range of human lung strength. So, in that way, it is not like a
siren.
Generally we are in agreement other than the fact that you appear to be much
more sure of your position even though there has been little scientific
study of the comparative level of sound production from the reed and the
"sound board" (reedplates and comb) of the harmonica. Be careful of your
arguments from silence. Lets remember that humility is key to winning
friends and influencing people.

While driving home today I was thinking about what a salesman did with my
brother in law when he bought his seagull guitar. To demonstrate the effect
of more finish on the guitar he put his hand on the sound board to show the
volume and tone difference resulting from adding something, like finish, to
the top. I am sure this is an analogy that is exagerated but I got out my
car aset of harmonicas and tried to play them with little hand contact and
felt the combs to see if they vibrated. (is this worse than talking on the
phone in the car?) In both metal and plastic I could feel no vibration in
the comb. On the other hand there was a volume and tone difference when I
removed my hand from the covers. Maybe we should spend more time on cover
material and design. Then my mind wandered to electric guitars and
resonance. And I wonder if that is a better analogy. The wood used on an
electric guitar effects the resonance of the strings. Might the comb
material have a similar effect? Again you may argue against it but all this
is hypothesis that is not tested.

And this conversation is going on and on. I am am continuing to contribute
Sorry. But if I think it in my car and nobody hears, did I really think it?

Derwood

On Mon, Sep 22, 2008 at 4:08 PM, Vern Smith <jevern@xxxxxxx> wrote:

>
> ----- Original Message ----- From: "Derwood Blues" <
> Derwood.Blues@xxxxxxxxx>
> To: "harp-l" <harp-l@xxxxxxxxxx>
> Sent: Monday, September 22, 2008 6:04 AM
> Subject: [Harp-L] Re: Combs
>
>
>  >From my understanding of physics (I am not a physicist) a siren spinning
>> creates a wave of air that based on the speed of the spin creates
>> different
>> notes. It is the moving air that is the noise. A guitar string plays a
>> particular note based on the length of the moving section of string, the
>> tightness of the string and the thickness. as you change the (wave) length
>> of the string you change the note. The top piece of wood on the guitar
>> picks
>> up that vibration and projects it. The wood also adds its own
>> characteristics to the sound.
>>
>
> So far, we are in agreement.
>
>
>  A harmonica reed is a certain length,
>> thickness and tightness. That combination creates the note. I would guess
>> that it is more like a guitar than a siren. If by "note", you mean pitch,
>> that is correct.
>>
>
> The reed determines the pitch/frequency like a guitar string.
>
>  If it was like a siren, the
>> velocity of your air would effect the note.
>>
>
> The reed generates the sound like a siren.  The pressure/velocity of the
> air does affect the loudness.
>
>  The question remains if the comb is actually transmitting some of the
>> volume
>> and therefore adding it's own characteristics to the note. I would guess
>> from the basic construction that the comb has little effect. Unlike a
>> guitar
>> the comb material is not designed/manipulated to produce sound. That does
>> not mean that it is irrelevant. I would guess that surface friction on the
>> airflow and the "solidness" of the comb connection to the reed plates
>> would
>> effect the sound or at least the response of the instrument to the player.
>>
>
> When you pluck a reed you hear some sound emanating from the reed as from a
> bell and from the comb-and-reedplate assembly as from a soundboard. However,
> three things make this sound very faint:
>
> 1. The vibrational energy of the reed is very low. This is the integral of
> the deflection of the reed times the force required to deflect it,  It is
> also the kinetic energy in the reed when it passes zero deflection.
>
> 2. The surface area of the reed is tiny compared to the surface of a bell
> or the soundboard of a guitar.
>
> 3. The Reedplates and comb of a harmonica make a very poor soundboard.  Not
> only does it have a small surface area but also it is laminated of different
> materials and filligreed with holes.  One could hardly design a poorer
> soundboard.
>
> Thus the very faint sound of the vibrating reed via the comb and reedplates
> is masked by the robust sound of the air chopped by the reed as it opens and
> closes the slot.  Masking is when a faint stimulus to a human sense is
> overwhelmed by a powerful one.  Sunlight masks starlight in the daytime. You
> can't hear a whisper near a moving train.  See
> http://en.wikipedia.org/wiki/Auditory_masking
>
>  But I cannot imaging that there is any money out there to test such
>> things.
>> On the other hand the effect of a guitar's material and design have an
>> obvious enough effect to result in the standards that are out there today.
>> A
>> solid top guitar has enough of a difference from a laminate that your
>> average guitarist can hear the difference.
>>
>
> That is true, but a harmonica doesn't work like a guitar.
>
> Vern
> Visit my harmonica website www.Hands-Free-Chromatic.7p.com
>
>
>
>