What note does a listener hear when a singer gulps helium and sings middle C?

In summary, the frequencies of helium and air are the same, but the velocities and wavelengths are different, so what is the equation relating them? The steps i did before is what my teacher did, he just solved it halfway and said that's the equation we use, so I am a bit confused because i calculated it to be 766Hz which is around the note G and then after some research i found that the note is still C but i guess a few octaves higher? not sure...really confusedif you want us to check your work, you'll have to show us your calculations.
  • #1
amit25
30
0

Homework Statement


Singer sings middle C. She then gulps helium and tries to sing the same note i.e her vocal chords remain the same. What note will the listener hear?





Homework Equations


f=velocity of air/lambda middle C



The Attempt at a Solution


f=velocity of air/lambda middle C
gives lambda=330m/s/262Hz=1.2595

After this point I am lost i think you have to use freq of helium=velocity of helium/lambda of middle C
but what note is that?
is it suppose to be C 4 octaves higher or the note G.
 
Physics news on Phys.org
  • #2
hi amit25! :smile:

you don't need to find the frequencies, they cancel out!

the frequencies are the same, but the velocities and wavelengths are different, so what is the equation relating them? :wink:

(and what is the ratio of wavelengths of middle C and the next C?)
 
  • #3
the steps i did before is what my teacher did, he just solved it halfway and said that's the equation we use, so I am a bit confused because i calculated it to be 766Hz which is around the note G and then after some research i found that the note is still C but i guess a few octaves higher? not sure...really confused
 
  • #4
if you want us to check your work, you'll have to show us your calculations. :wink:
 
  • #5
okay this is what i did

f=velocity of air/lambda middle C

262Hz=330m/s / lambda middle C

which gives lamba=1.2595 m

frequency of helium is f=velocity of helium/lambda

f=965m/s/1.2595m
f=766Hz
 
  • #6
amit25 said:
okay this is what i did

f=velocity of air/lambda middle C

262Hz=330m/s / lambda middle C

which gives lamba=1.2595 m

frequency of helium is f=velocity of helium/lambda

f=965m/s/1.2595m
f=766Hz

ok so far (but it would be a lot quicker not to find either of the wavelengths)

now what is the ratio of wavelengths of middle C and the next C?
 
  • #7
oh okay I am just trying to do it the way my teacher did
but the ratio is 132cm/65.9cm=2
 
  • #8
amit25 said:
… the ratio is 132cm/65.9cm=2

now compare that with the ratio of the two wavelengths in the question :smile:
 
  • #9
233Hz/294Hz=0.80
which is less than the wavelength ratio
 
  • #10
amit25 said:
233Hz/294Hz

where do those figures come from? :confused:
 
  • #11
Wavelength in helium λ = c / f = 927 / 262 = 3.538 m.
Wavelength in air λ = c / f = 343 / 262 = 1.309 m.

Ratio = 3.538 / 1.309 = 2.7
 
  • #12
amit25 said:
Wavelength in helium λ = c / f = 927 / 262 = 3.538 m.
Wavelength in air λ = c / f = 343 / 262 = 1.309 m.

Ratio = 3.538 / 1.309 = 2.7

where do 927 and 343 come from? :confused: :confused:
 
  • #13
927 is the speed of helium and 343 is the speed of sound
 
  • #14
what were the 330 and 965 you used before? :confused:
 
  • #15
those are the same values i just researched to get more accurate values
 
  • #16
ok, if the frequency ratio is 2.7, and the lower note is middle C, then how do we work out the higher note?
 
  • #17
so 2.7 x 262hz=707hz so that's F5 note ?
 
  • #18
amit25 said:
so 2.7 x 262hz=707hz so that's F5 note ?

what's F5 ? :confused: do you mean F# ? and which octave ?

and how did you work it out?

or did you just look it up in a table? :redface:
 
  • #19
from here not sure which octave anyways i think its wrong the answer should still be C
http://www.sengpielaudio.com/calculator-… [Broken]
Scroll down to "Frequency to Musical Note Converter".
 
Last edited by a moderator:
  • #20
amit25 said:
from here not sure which octave

you won't be able to take that website into the exam with you :redface:

(btw, that link isn't working)

you need to know how to calculate it yourself

if the ratio was 2 (instead of 2.7), what would the note be?

if the ratio was 4, what would the note be?
 
  • #21
lol well i have a sheet we got with all the notes and frequency so i don't think were expected to memorize them, anyways thanks i feel like this is going no where ill just ask my professor
 

What are waves of sound from a singer?

Waves of sound from a singer refer to the vibrations created by a singer's vocal cords that travel through the air as sound waves. These waves can be perceived by our ears as music or speech.

How are these waves created?

These waves are created by the vibration of the vocal cords in the larynx, which is located in the throat. As air passes through the vocal cords, they vibrate and produce sound waves.

What factors affect the waves of sound produced by a singer?

The pitch and volume of a singer's voice can be affected by factors such as the tension and thickness of their vocal cords, the shape of their vocal tract, and the amount of air they expel while singing.

How do these waves of sound travel to our ears?

Once the sound waves are created by the singer, they travel through the air as longitudinal waves, which means the particles of air move back and forth in the same direction as the wave. These waves then enter our ear canal and cause our eardrums to vibrate, sending signals to our brain that we perceive as sound.

Can different types of singers produce different types of waves of sound?

Yes, different types of singers can produce different types of waves of sound depending on their vocal techniques and styles. For example, opera singers may produce longer and more powerful waves of sound compared to pop singers who may produce shorter and more varied waves of sound.

Similar threads

  • Introductory Physics Homework Help
Replies
27
Views
3K
  • MATLAB, Maple, Mathematica, LaTeX
Replies
1
Views
2K
Back
Top