Session 10: Class Activities and Resources

This week we look at the low-frequency behaviour of rooms.

FIRST TASK

Do you make music at home? In your bedroom? Write down the dimensions of your production space and bring to class, let's find out what the bass is doing in your room.

Length:

Width:

Height:

Listening Exercise: Class Activity

PART 1: How does the sound change as we move around the room?

• As music plays from the classroom loudspeakers, move around the room and listen.

• Focusing on the frequency content, how does the sound change between centre, front, back, sides and even in the corners of the room?

How can we explain this change, if any? Which location is "correct"?

PART 2: Now, let's see if we can use some basic maths to explain what we have just experienced...

• Using this info about Standing Waves, find the fundamental resonant frequency for the width of the room

• Move around the room once more, how do the sounds change?

• Does that match up with our experience when listening to music around this room?

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Analysis exercise: Group activity

As per lecturer's instructions, break into groups and complete the Standing Wave Sheet for other rooms on campus (Studio control room/live room, available classrooms).

You will need:

- SPL Meter

- Tape Measure

- Pen and Standing Wave Sheet

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Individual work on Project 3

Using the dimension of your bedroom/production space at home as collected for this week's pre-class activity, find:

• Cut-off frequency

• First axial mode for each dimension (standing wave)

• Critical Frequency

Use independent research as well as ROOM MODE ANALYSIS SPREADSHEET - note this does need to be opened with Microsoft Excel to function properly.

FURTHER RESOURCES:

Matlab: https://www.mathworks.com/help/matlab/ref/waterfall.html

Standing Waves: http://www.sengpielaudio.com/StandingWaves.htm

Room Modes: http://www.sengpielaudio.com/calculator-roommodes.htm

Room Mode Online Calculator: http://www.submersiblestudios.com/studio_acoustics/room-mode-calculator/

Room Mode Online Calculator: https://amcoustics.com/tools/amroc?l=400&w=500&h=600&r60=0.6

REALLY awesome online room mode calculator: https://amcoustics.com/tools/amroc?l=280&w=300&h=400&r60=0.6

RT60 Room Calculator: https://www.troldtekt.com/web-tools/acoustics-calculator/