Taking SPL reading question...

[elastic]

Hi all,

I’m building a garden studio, I’m currently in a 3 x 4m bedroom upstairs in a house. I would like to take an SPL Reading so I know what kind of isolation I will require when I build my new studio down the bottom of my garden.

I plan to turn my music up to the level I generally work at then take some readings, so -

Where should I take the readings? I read 3ft outside the room, so is the landing ok to take a reading from? any others distances or ideas here?
(When the studio is built, my neighbours fences will be about 2-4m away, there houses will be a good 20m away approx)

I have an SPL reader app on my iPhone, see pic, will that be ok to use?

Thank you for any help and advice

[Soundman2020]

I have an SPL reader app on my iPhone, see pic, will that be ok to use?

It's not ideal, and won't be very accurate, but it's OK for just getting a rough idea at this stage. Make sure that you set it to use "C" weighting and "Slow" response.

Take measurements in several places around the building, both inside and out. Start off inside the room with your loud music playing. Hopefully you have a good full-range speaker system. Play bass-heavy music in there, at about 100 dBC if you can (measured inside the room, at least 3 feet away from the speakers)--- wear hearing protection!

The go outside and close the doors and windows, and measure at many locations, close by and far away. Keep careful notes of exactly where you are for each measurement, and exactly what the level was at that location. Pay special attention to the points closest to your neighbor's at your property line.

Then go back inside, turn off the music, and wait for a very quiet time of day. Go back to each of the locations where you measured before, and note down the level again for this "quiet time". For each location, subtract the "quiet" number from the "loud" number: the resulting number is how much EXTRA isolation you need, above and beyond what you are getting now, assuming that you want to be practically inaudible at each of those locations. And the difference between the level INSIDE the room and the "loud" level, is the amount of isolation you are getting at present, for each location.

All that data should help you make some intelligent decisions about what type of isolation you need, so you can start designing!

- Stuart -

[elastic]

Thank you so much Stuart, superb advice as always!

Quick question -

Does dbC mean use my Db meter app with the 'C' rating?

My current bedroom studio is not on the site of where my new one is. Theres not much i can do about that obviously.

For the outside readings i plan to take, i figure I only need to take readings at around 2-5m outside of the current studio, because thats the closest distance my neighbours will be in the new setup.

I should say, im way down the bottom of my garden in the new setup, so although 2-5m will be close to them, they won't be down the bottom of the garden most of the time as the house's are about 30m up the garden.

hope that makes sense.

[Soundman2020]

Does dbC mean use my Db meter app with the 'C' rating?

Right! dBA is short for "decibels SPL, A-weighted", and dBC is short for "decibels SPL, C-weighted".

My current bedroom studio is not on the site of where my new one is. Theres not much i can do about that obviously.

Do the tests where the new room will be, not where the current room is.

For the outside readings i plan to take, i figure I only need to take readings at around 2-5m outside of the current studio, because thats the closest distance my neighbours will be in the new setup

I would still take measurements at many locations outside, to be sure that you have a good set of valid data. You might even notice unexpected issues, such as one area where the levels are louder than expected, possibly indicating a weak spot in your current isolation...

I should say, im way down the bottom of my garden in the new setup, so although 2-5m will be close to them, they won't be down the bottom of the garden most of the time as the house's are about 30m up the garden.

Ahh yes, but the law doesn't care where they are or where you are! It just cares about levels at the locations specific in the regulation itself. Usually, that means at your property line, at the point closest to the sound source (your studio), even if that is a silly location. So if your neighbor does complain, and the inspector comes out to visit, he'll do the testing at the least-favorable point for you, even if it is a spot where no person would ever be (eg, in the middle of a bush, or behind a tree, or on top of a garbage can). The inspector is not your friend, and won't make things easy for you by measuring at reasonable locations... So assume the worst when you measure, and check several points along your property line.

- Stuart -

[elastic]

apologies if i'm getting mixed up, but how can i do the readings where the new studio will be as i haven't even built the new studio yet?

[elastic]

Really struggling to figure out how to do these tests on the proposed studio space as I haven’t even built the studio yet?

[elastic]

So i took a reading on the plot of land where the new studio will be. I went out when it was generally a quiet time, 9pm - At my neighbours fence it read 45dbc (i used an spl meter app on my phone with it set to slow and 'c' rating)

I measured what i work at in my studio and its generally around 80dbc

I am not concerned with sound coming into the studio as i am not mic'ing/recording anything inside and its generally quite quiet.

Attached is a pic of the land... it measures 10m wide by 11m deep

[elastic]

Hi Stuart, can you recommend a good suitable SPL meter for doing my tests please?

I'm not 100% confident with the iPhone app.

Many thanks for your time and help

[Soundman2020]

Hi Stuart, can you recommend a good suitable SPL meter for doing my tests please?

I'm not 100% confident with the iPhone app.

Many thanks for your time and help

There's a thread I wrote a while back on how to use REW, which you don't need to do yet, but in that thread I mention how to choose a good meter. Take a look at just that part of the tutorial, about meters: http://www.johnlsayers.com/phpBB2/viewt ... =3&t=21122 .

- Stuart -

[elastic]

Thanks, will do.

I just ordered this one -

https://www.amazon.co.uk/Handheld-Measu ... B01M32WX3H

[elastic]

So I took my reading with my new spl meter, slow and c rating -

In my current studio where I sit, it’s about 95dbc when I turn it up loud, generally I work between 80-90dbc but I will go with 95 as my reading as I do go to that level sometimes.

In the garden where the new studio will be built it measured 50dbc at 8pm - fair few birds chirping around.

So, am I correct in thinking I need 45db of isolation?

I’m in England and this is what the government website says -

The permitted noise level using A-weighted decibels (the unit environmental noise is usually measured in) is:

34 dBA (decibels adjusted) if the underlying level of noise is no more than 24 dBA
10 dBA above the underlying level of noise if this is more than 24 dBA

Just struggling to get a grip on exactly what isolation I require. Apologies if this seems trivial or easy, I’m just not great at things like this.
Thanks

[Waka]

So I took my reading with my new spl meter, slow and c rating -

In my current studio where I sit, it’s about 95dbc when I turn it up loud, generally I work between 80-90dbc but I will go with 95 as my reading as I do go to that level sometimes.

In the garden where the new studio will be built it measured 50dbc at 8pm - fair few birds chirping around.

So, am I correct in thinking I need 45db of isolation?

I’m in England and this is what the government website says -

The permitted noise level using A-weighted decibels (the unit environmental noise is usually measured in) is:

34 dBA (decibels adjusted) if the underlying level of noise is no more than 24 dBA
10 dBA above the underlying level of noise if this is more than 24 dBA

Just struggling to get a grip on exactly what isolation I require. Apologies if this seems trivial or easy, I’m just not great at things like this.
Thanks

Sorry noone's got back to you. I managed to miss your post elastic!

For legal requirements you need to measure A-Weighted. So your 50dBC is not the measurement you want. Measure A weighted for legal commitments, and measure C weighted for yourself. C is better practically speaking for how the sound will be perceived.

You need the level of noise you produce at your boundary to be no more than 10 dBA above ambient levels. So if you measure 50dBA (A not C weighting) at the time of day you will be using your studio (the quietest time you will be using it) then you need to be less than 60dBA at your boundary when using your studio. If you measure 40dBA in ambient levels, then you need to be no more than 50dBA at your boundary etc. It's best to measure at night time when there is little noise. Try and pick a time when birds aren't chirping etc. Usually it will be around 30-35 dBA in ambient levels depending on proximity to motorways etc.

If you have high ambient levels, for example >40dBA, your legal requirments are easy to achieve (getting down to 50dBA when you mix at 85dBA is easy.). But then you choose an isolation requirement that will be reasonable for you to achieve and to keep the peace with your family/neighbours. You might not be breaking laws, but still could be annoying the neighbours if you just stick to the letter of the law.

I would aim for 40dBA at your boundary if you could personally. Then there will be almost no noticeable noise for neighbours to complain about.

Dan