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### Re: Sounds of Music C

Posted: April 1st, 2019, 5:00 am
What resources awe you guys using fow studying decibels? I'm trying to hewp my team figure it out but it's super confusing...
The wikipedia page might be helpful and thewe's also a hyperphysics page on it: http://hyperphysics.phy-astr.gsu.edu/hb ... ntens.html

Basically, the point of decibels is to measure sound intensity in a way that is closer to how we perceive loudness, which is why it varies logarithmically with W/m^2. So if you hear a sound as twice as loud as another, the fiwst one is roughly twice the numbew of decibels, not twice the W/m^2.

Because decibels awe supposed to be mowe related to human hearing, that is also why $I_0$ is the value that it is. $I_0$ is roughly the minimum sound intensity humans can hear, so if the intensity is at $I_0$ (so if $I=I_0$), then $10log(I/I_0) = 10log(I_0/I_0) = 10log(1) = 0 dB$. This makes 0 dB the minimum intensity humans can hear.

I'm not sure what pawt of it specifically is confusing you, but I hope this sort of genewaw overview helps.
We never studied logs, so that's the hardest pawt. I'm still a little unsure of the difference between sound intensity, sound pressure, and sound pressure level. wike...why awe thewe three different ways of describing the same thing? Also, my team saw a question on an invite test about how many decibels something was "twice as loud" and the answer apparently wasn't twice the decibels. Maybe it was "twice as intense"? Does that make a difference?

Also.....fow some reason my browser is changing r's into w's and I can't figure out what the heck is going on. It's actually kind of amusing.
Usually if they say twice as loud they're talking about sound intensity, so it would be log(2) times the decibels. Still, sometimes it can be kind of vague and you just have to use your best judgement.

And yeah, the whole website appears to have been OwO'ed for April fools

Edit: actually it would be plus 10log(2) decibels not times log(2) since it's decibels (hence the 10) and multiplying the inside of the log translates to addition outside of it.

### We: Sounds of Music C

Posted: April 1st, 2019, 12:46 pm
What wesouwces awe you guys using fow studying decibels? I'm trying to hewp my team figure it out but it's super confusing...
The wikipedia page might be helpful and thewe's also a hyperphysics page on it: http://hyperphysics.phy-astr.gsu.edu/hb ... ntens.html

Basically, the point of decibels is to measure sound intensity in a way that is closer to how we perceive loudness, which is why it varies logarithmically with W/m^2. So if you hear a sound as twice as loud as another, the fiwst one is roughly twice the numbew of decibels, not twice the W/m^2.

Because decibels awe supposed to be mowe related to human hearing, that is also why $I_0$ is the value that it is. $I_0$ is roughly the minimum sound intensity humans can hear, so if the intensity is at $I_0$ (so if $I=I_0$), then $10log(I/I_0) = 10log(I_0/I_0) = 10log(1) = 0 dB$. This makes 0 dB the minimum intensity humans can hear.

I'm not sure what pawt of it specifically is confusing you, but I hope this sort of genewaw overview helps.
We never studied logs, so that's the hardest pawt. I'm still a wittle unsure of the difference between sound intensity, sound pressure, and sound pressure level. wike...why awe thewe thwee different ways of describing the same thing? Also, my team saw a question on an invite test about how many decibels something was "twice as loud" and the answer apparently wasn't twice the decibels. Maybe it was "twice as intense"? Does that make a difference?

Also.....fow some reason my browser is changing r's into w's and I can't figure out what the heck is going on. It's actually kind of amusing.
Sound pressure is the measure of the amount of pressure (basically, a measure of force) at a certain area, or how much the air is being pushed and pulled. Sound pressure level is a logarithmic measure of the same thing. Sound intensity on the other hand is a measure of how much energy is transferred through a certain area and how quickly it is being transferred. Hearing and microphones are typically directly affected by sound pressure, which is related to the sound intensity.

Decibels being a logarithmic unit means that the change from 0 dB to 10 dB is multiplying 10 instead of adding 10. This allows us to specify a very wide range of volumes, which is good because the human ear can detect a wide range of volumes! If we want something to be ten times as loud, we have to increase the number of decibels by ten decibels. If we want something to be a hundred times as loud, we have to increase the number of decibels by twenty decibels. If we want something to be a thousand times as loud, we have to increase the number of decibels by thirty decibels. If we want something to be, say, 42 times as loud, it gets trickier. We have to figure out how many times 10 goes into 42: $10^? = 42$. This is where logarithms become useful. A logarithm "undoes" the exponent so we end up with something like this: $? = \log 42$ (said out loud, log of 42, or log base 10 of 42). This is something that your calculator can calculate! (Before calculators, people looked them up in big reference sheets). $\log 42 \approx 1.623$. This means that to get something 42 times as loud, we add $10 * 1.623 = 16.23$ decibels. Similarly, to get something twice as loud, we add $10 * \log 2 = 3.01$ decibels. Looking up "logarithmic scale" might help you visualize this better.

### Re: Sounds of Music C

Posted: April 4th, 2019, 7:59 pm
If anyone is from San Joaquin Regionals in NorCal, did they use Google Sci Jounal? From what I know San Joaquin ES might be running NorCal States and the possibility of Google Sci Journal is making me very nervous.

### Re: Sounds of Music C

Posted: May 11th, 2019, 1:28 pm
Does anyone know what tuning software will be used at nationals?

### Re: Sounds of Music C

Posted: May 11th, 2019, 8:24 pm
Does anyone know what tuning software will be used at nationals?
Check soinc, that will give it away.

### Re: Sounds of Music C

Posted: May 15th, 2019, 4:04 am
If I’m playing a3-a4 when they are testing for pitch accuracy, is it okay if I play like G6 for the decibel test? or does it have to be a note within the octave and key of the pitch test?

### Re: Sounds of Music C

Posted: May 15th, 2019, 5:02 am
If I’m playing a3-a4 when they are testing for pitch accuracy, is it okay if I play like G6 for the decibel test? or does it have to be a note within the octave and key of the pitch test?
Must be a note from the pitch test.

### Re: Sounds of Music C

Posted: May 15th, 2019, 5:27 am
If I’m playing a3-a4 when they are testing for pitch accuracy, is it okay if I play like G6 for the decibel test? or does it have to be a note within the octave and key of the pitch test?
Must be a note from the pitch test.
Thank you

### Re: Sounds of Music C

Posted: May 15th, 2019, 1:00 pm
Hi guys, as I mentioned in the Nationals thread, my team is currently signed up for the 12pm time slot for sounds. However, we need the 9:30 am slot in order for both of our members to compete. If anyone currently has the 9:30 slot and can either accommodate the 12pm slot or is willing to work something out, please contact me.

### Re: Sounds of Music C

Posted: May 16th, 2019, 8:58 pm
What teams are good in sounds going to nats?