DRUM SETS CHARACTERIZATION IN ACOUSTIC LABORATORY ...

Proceedings of the Second Vienna Talk, Sept. 19−21, 2010, University of Music and Performing Arts Vienna, Austria

DRUM SETS CHARACTERIZATION IN ACOUSTIC LABORATORY Nicola Granzotto, Paolo Ruggeri Department of Applied Physics University of Padova, Italy [email protected] calibrator B&K 4231, power amplifier omnidirectional source B&K 4295.

ABSTRACT This work presents the measurement results of two drum sets (one for professional use and the other one for beginners use), played by two different drummers, carried out in the Acoustics Laboratory of the Department of Applied Physics of the University of Padova (Italy). The sound power of these drum sets has been evaluated in reverberation room, according to the methods indicated in the ISO 3741 Standard. Six common and simple drum patterns, with different rhythm speed have been played (120 BPM and 60 BPM). Then, some comparisons have been made between the whole sound power level of the drum sets, and each single drum piece of the drum set separately played. The relative third octave bands Aweighted spectrums of six grooves has been calculated in order to calculate spectrum adaptation terms for predicting the A-weighted sound pressure level in a receiving room. According to the methods indicated in the ISO 140-3 Standard [2], sound insulation has been measured using a drum set instead of a omnidirectional source.

2.2

2716,

Drums, drummer and grooves

For the measurements of the sound power level, two basic drum sets have been used, one for professional use and another one for beginner use, with the following characteristics: Table 1: Description of drum sets Model Bass drum Snare drum Hi-Hat Ride

Professional drum set SONOR Signature SONOR wood 22”x18” SONOR wood 14”x8” ZILDJIAN K/Z 13” ZILDJIAN K Custom 20 ”

Beginners drum set PEARL EX825P Export Drum PEARL wood 22”x16” PEARL wood 5-1/2” PEARL Cymbal 14” PEARL Cymbal 18”

Ride/Crash

Hi Hat

1. INTRODUCTION Acoustics drums set instruments produce very high sound pressure level, depending on the type and quality of the drums and cymbals and of the drummer. It depends also by the groove and by the BPM (beat per minute) of the groove.

Bass Drum

2. MEASUREMENTS 2.1

B&K

Snare Drum

Figure 1: Basic Drum set in the reverberation room

Sound power level of acoustic drum sets

Every drum set was played by two drummers, one with a school background (drummer 1) and the other one self-taught (drummer 2).

Sound power level, Lw, of a acoustic source is a characteristic of a source and doesn’t depend on distance and room absorption. The sound power level of acoustic drum sets was determined in laboratory according to ISO 3741 Standard [1]. It is calculated by the following equation: ⎛ A A S ⋅c ⎪⎧ Lw = Lp + ⎨10lg + 4,34 + 10 lg ⎜1 + A0 S ⎝ 8 ⋅V ⋅ f ⎩⎪

⎡ 427 ⎞ 273 B ⎤ ⎪⎫ ⎥ − 6⎬ [dB] ⎟ − 25lg ⎢ ⎠ ⎣ 400 273 + θ B0 ⎦ ⎭⎪

(1)

where: Lp is the mean sound pressure level in the reverberation room [dB]; A is the equivalent absorbing area of the room [m2]; A0 =1 m2; S is the surface of the reverberation room [m2]; V is the volume of the reverberation room [m3]; f is the third octave band frequency [Hz]; c is the sound velocity at the temperature θ [m/s]; θ is the temperature [°C]; B is the atmospheric pressure [Pa]; B0 = 101300 [Pa].

Figure 2: Drummer 1 and drummer 2 play Sonor and Pearl drums in the reverberation room Six basic grooves are chosen. Every groove was played at 120 BPM and 60 BPM for 20 seconds. Single piece was also played using the same grooves.

For the measurements it has been used a 4 channels Svantek 948 sound analyzer, microphones B&K 4188, microphone

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Table 2: Grooves played

120

Groove

120BPM Pearl (1) Crash + SN Lw=117,2dB

Notation

1

“CHH+SN” (cloded Hi-Hat with snare drum)

2

“OHH+SN” (open Hi-Hat with snare drum)

3

“CHH+SIDE” (cloded Hi-Hat with side stick)

4

“CRASH+SN” (4/4 board cymbal with snare drum)

5

“RIDE+SN” (Ride cymbal with snare drum)

120BPM Sonor (1) Crash + SN Lw=116,7dB 120BPM Sonor (2) Crash + SN Lw=117,3dB

100

60BPM Pearl (1) Crash + SN Lw=114,9dB 60BPM Pearl (2) Crash + SN Lw=111,9dB

90

60BPM Sonor (1) Crash + SN Lw=114,8dB 60BPM Sonor (2) Crash + SN Lw=113,4dB 5000 Hz

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“RIDE+SIDE” (Ride cymbal with side stick)

6

120BPM Pearl (2) Crash + SN Lw=115dB

110 Sound Power Level [dB]

n°

Frequency [Hz]

2.3

Figure 6: Sound power level of groove 4 at 120 and 60 BPM

Experimental results

In the following graphics are presented the sound power level of acoustic drum sets, with different groove and BPM.

120 120BPM Pearl (1) Ride + SN Lw=115,8dB

Sound Power Level [dB]

120

120BPM Pearl (2) CHH + SN Lw=110,3dB

110

120BPM Sonor (1) CHH + SN Lw=115,7dB 120BPM Sonor (2) CHH + SN Lw=112,6dB

100

120BPM Sonor (1) Ride + SN Lw=115,8dB 120BPM Sonor (2) Ride + SN Lw=113,5dB

100

60BPM Pearl (1) Ride + SN Lw=113,1dB 60BPM Pearl (2) Ride + SN Lw=108,2dB

90

60BPM Sonor (1) Ride + SN Lw=113dB

60BPM Pearl (1) CHH + SN Lw=113,3dB 60BPM Pearl (2) CHH + SN Lw=107,4dB

60BPM Sonor (2) Ride + SN Lw=110,9dB

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120BPM Pearl (2) Ride + SN Lw=112,2dB

110

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120 120BPM Pearl (1) Ride + Side Lw=106,5dB

Figure 3: Sound power level of groove 1 at 120 and 60 BPM Sound Power Level [dB]

120 120BPM Pearl (1) OHH + SN Lw=116,1dB 120BPM Pearl (2) OHH + SN Lw=113,7dB 120BPM Sonor (1) OHH + SN Lw=115,9dB 120BPM Sonor (2) OHH + SN Lw=113,7dB

100

120BPM Sonor (1) Ride + Side Lw=107,8dB 120BPM Sonor (2) Ride + Side Lw=107,7dB

100

60BPM Pearl (1) Ride + Side Lw=103,8dB 60BPM Pearl (2) Ride + Side Lw=104,8dB

90

60BPM Sonor (1) Ride + Side Lw=105,7dB

60BPM Pearl (1) OHH + SN Lw=113,2dB 60BPM Pearl (2) OHH + SN Lw=109,8dB

60BPM Sonor (2) Ride + Side Lw=107,1dB

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60BPM Sonor (2) OHH + SN Lw=111,7dB

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60BPM Sonor (1) OHH + SN Lw=113,2dB

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120BPM Pearl (2) Ride + Side Lw=107,7dB

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In the following graphics are presented an example of time history of the sound pressure level in the reverberation room.


120

120BPM Pearl (2) CHH + Side Lw=107,7dB

115

120BPM Sonor (1) CHH + Side Lw=106,9dB 120BPM Sonor (2) CHH + Side Lw=107,9dB 60BPM Pearl (1) CHH + Side Lw=103,9dB 60BPM Pearl (2) CHH + Side Lw=103,8dB 60BPM Sonor (1) CHH + Side Lw=104,3dB 60BPM Sonor (2) CHH + Side Lw=105,6dB

100

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Time [x0,1 s] CHH+SN Pearl (1) 120BPM - Short Leq CHH+SN Pearl (2) 120BPM - Short Leq CHH+SN Sonor (1) 120BPM - Short Leq CHH+SN Sonor (2) 120BPM - Short Leq

Frequency [Hz]


CHH+SN Pearl (1) 120BPM - Leq CHH+SN Pearl (2) 120BPM - Leq CHH+SN Sonor (1) 120BPM - Leq CHH+SN Sonor (2) 120BPM - Leq

Figure 9: Sound pressure level of groove 1 at 120

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120BPM Pearl (1) CHH + Side Lw=107,2dB

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Single event, SELwA, can be used to estimate global Aweighted sound power level of a drum groove using the following equation:

Sound pressure level [dB]

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LwA _ groove

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⎛ ⎛ E ⋅ BPM ⎞ ⎞ ⎞ ⎛ ⎜ SELwAi +10lg ⎜ ⎟⎟ ⎝ 240⋅TS ⎠ ⎟ ⎜ ⎜ ⎟ ⎜ ⎟ 10 ⎜ ⎟⎟ ⎜ ⎝ ⎠ = 10 lg ⎜ ∑ i 10 ⎟ ⎜ ⎟ ⎜ ⎟ ⎝ ⎠

[dB( A)]

(3)

Time [x0,1 s] CHH+SN Pearl (1) 60BPM - Short Leq CHH+SN Pearl (2) 60BPM - Short Leq CHH+SN Sonor (1) 60BPM - Short Leq CHH+SN Sonor (2) 60BPM - Short Leq

CHH+SN Pearl (1) 60BPM - Leq CHH+SN Pearl (2) 60BPM - Leq CHH+SN Sonor (1) 60BPM - Leq CHH+SN Sonor (2) 60BPM - Leq

where: SELwAi is the single event A-weighted sound power level [dB(A)]; E is the number of musical event in a measure; BPM is beat per minute; TS is the time signature.

Figure 10: Sound pressure levels of groove 1 at 60 BPM It can be noted that different drummers play with different sound power levels.

For example for a heavy metal groove (Figure 12) at 130 BPM with 16/16 double bass drum, we can estimate the global sound power level by this:

Single drum set piece sound power level has been also measured and summed. It has been found quite the same sound power level of total groove (example of “Ride+SN” in Figure 11). ⎛ LP _ SD ⎞ ⎛ LP _ Ride ⎞ ⎛ ⎛⎜⎜ LP _ BD ⎞⎟⎟ ⎞ ⎜⎜ 10 ⎟⎟ ⎜⎜ 10 ⎟⎟ 10 ⎠ ⎠ ⎠⎟ Lsum = 10 lg ⎜ 10⎝ + 10⎝ + 10⎝ ⎜ ⎟ ⎝ ⎠

⎛ ⎛ ⎛ 4⋅130 ⎞ ⎞ ⎛ 8⋅130 ⎞ ⎞ ⎞ ⎛ ⎛⎜ 101,4+10lg⎛⎜ 16240⋅130⋅1 ⎞⎟ ⎞⎟ ⎜ 109,0 +10lg ⎜ ⎜ 91,3+10lg ⎜ ⎟⎟ ⎟⎟ ⎝ ⎠⎟ ⎝ 240⋅1 ⎠ ⎟ ⎝ 240⋅1 ⎠ ⎟ ⎜ ⎜ ⎜ ⎜⎜ ⎟ ⎟ ⎜ ⎟ ⎜ ⎟ 10 10 10 ⎟ ⎜ ⎟ ⎜ ⎟⎟ ⎜ ⎜⎝ ⎠ ⎠ ⎠ LwA = 10lg ⎜10 + 10⎝ + 10⎝ ⎟= ⎜ ⎟ ⎜ ⎟ ⎝ ⎠ = 114,7 [dB( A)]

(2)

[ dB ]

120

(4)


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Ride + SN

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sum 90

Figure 12. Heavy metal groove

bd SN

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Ride

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Figure 11. Sound power level of groove “Ride+SN” at 120 BPM and the energetic sum of single piece

2.4

⎛S⎞ R = L1 − L2 + 10 lg ⎜ ⎟ ⎝ A⎠

Prediction of drums grooves A-weighted sound power level

From the measurements of single piece, it has been calculated the mean single event A-weighted sound power level by two drum sets and two drummers, SELwA, (power level normalized to one second).

Hard Bass Drum Soft Bass Drum Snare Drum Closed Hi Hat Open Hi Hat Crash Ride Side Snare Drum

[dB ]

(5)

where: L1 is the mean sound pressure level in the transmitting room [dB]; L2 is the mean sound pressure level in the receiving room [dB]; A is the equivalent absorbing area of the receiving room [m2]; S is the surface of the separating wall [m2].

Table 2: mean single event A-weighted sound power levels by two drum sets and two drummers Piece

Sound reduction index measurements

Measurements of sound reduction index, R, of a wall were taken using an omnidirectional source, according to ISO 140 part 3 Standard [2], and a drum set with “CHH+SN” (groove 1). R is calculated by the following equation:

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SELwA 101,4 dB(A) 96,0 dB(A) 109,0 dB(A) 91,3 dB(A) 98,7 dB(A) 108,1 dB(A) 98,9 dB(A) 100,4 dB(A)

Figure 13: Measurement of sound reduction index of a wall using omnidirectional sound source and using drums set (groove 1 in transmitting room).

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0

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CHH + SN

OHH + SN

Relative spectrum [dB]

Omnidirectional source

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CHH + Side -20 Crash + SN

Ride + SN

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Figure 17: Relative spectrums (normalized to 0 dB) for “drums grooves spectrum adaptation terms” calculation

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Figure 14: Sound reduction index of a wall using omnidirectional sound source or drums set

We can use Rw+”Cdr” to estimate A-weighted sound pressure level in a receiving reverberant room, or to choose the best wall for sound insulation (for example if we have to project a drums insulation box, we haven’t to choose only the higher Rw value but we have to choose the higher Rw+”Cdr” value). The weighted sound reduction index, Rw, of 58 dB and “Cdr” of -8 dB has been measured for a light wall in laboratory and groove 1. In the transmitting and receiving room, the Aweighted sound pressure levels of respectively 108,1 dB(A) and 58,4 dB(A) has been measured. Predicted A-weighted sound pressure levels in the receiving room, Lp2(A), is:

The weighted sound redution index was Rw(C;Ctr)=58(-3;-10) for both source, so sound reduction index doesn’t depend on the drums sound.

2.6

Drums grooves spectrum adaptation terms

It has been found that the frequency distribution of sound power levels dosen’t change very much by changing BPM, and drummers (Figure 15).

Lp1( A) − (Rw +"Cdr ") =108,1− (58 −8) = 58,1 [dB( A)]

(6)

120 120BPM Pearl (1) CHH + SN Lw=114,9dB


110

100

well according to measurements.

3. CONCLUSIONS


The comparison between two drums sets played by two drummers show a relation between sound power level and BPM. In fact, doubling the BPM sound power level increase up to 3. It is noted that adding sound power level of single piece get the sound power level of entire groove. It has been calculated the mean single event A-weighted sound power level, SELwA, to predict the A-weighted sound power level of any groove. It is find sound power level of different groove and six normalized to 0 dB spectrum for “drums grooves spectrum adaptation terms” calculation useful for predicting sound pressure level in a receiving room produced by a particular drums groove in a transmitting room or to choose the best wall for a particular groove.

90 60BPM Pearl (1) CHH + SN Lw=113,3dB

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Figure 15: Example of sound power level changing BPM and drummers So, average sound power levels of the six grooves have been calulated (Figure 16) to find normalised to 0 dB spectrums (Figure 17). This is useful for “drums grooves spectrum adaptation terms” calculation, we call this parameter “Cdr” in analogy with ISO 717-1 method [3].

4. REFERENCES [1] ISO 3741 Acoustics. Determination of sound power levels of noise sources using sound pressure. Precision methods for reverberation rooms.

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[2] ISO 140-3 Acoustics. Measurement of sound insulation in buildings and of building elements. Part 3: Laboratory measurements of airborne sound insulation of building elements.

OHH + SN

CHH + Side 90 Crash + SN

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[3] ISO 717-1 Acoustics. Rating of sound insulation in buildings and of building elements. Part 1: Airborne sound insulation.

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Figure 16: Average sound power level of different gooves

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