29
Bose
®
Modeler
®
6.5 Software Tutorial
Chapter 5: Predicting Sound 81
Chapter 5: Predicting Sound
The primary function of Modeler software is to design a sound
system by observing predictions about the quality of sound in your
room. After you have created a model and placed listeners and
loudspeakers, you can take advantage of the powerful acoustic
simulation capabilities of Modeler software.
Modeler software has numerous features that provide insight into
the quality of sound in your model. Coverage maps are an easy
way to visually evaluate the sound, while other tabs and tools
provide additional visual and quantitative data. This chapter
provides an overview of how to use and interpret this data.
The examples in this chapter use the First Street Church project
that you copied from the installation CD to your desktop in
Chapter 1.
Follow these steps to open the Design 1 church model:
1. Click File > Open Project...
2. In the Look in: drop-down menu click on the desktop (see
Opening the sample model, on page 4, if you did not complete
Chapter 1).
3. Open the Tutorial folder, then open the First Street Church
folder.
4. Open the file named First Street Church.pjt.
5. In the Project window, double-click on the Design 1 model.
36
Bose
®
Modeler
®
6.5 Software Tutorial
82 Chapter 5: Predicting Sound
Room Acoustics
Getting ready
Before we start predicting the performance of the sound system,
anumber of parameters related to the environment and the
acoustics should be set. These parameters are all conveniently
located in the Acoustics tab.
1. Click on the Acoustics tab in the Detail window:
Figure 5.1 - Acoustics tab
This window contains the following:
See Acoustics tab, on page 396, for more information.
Temperature:
The ambient temperature in the room.
Humidity:
The humidity in the room.
Occupancy:
The number of people in the room.
House Curve:
A pre-determined target room-response
curve.
Background Noise:
The background noise in the room.
RT
60
:
The room’s reverberation time: based on
the amount of time it takes for a sound
pressure in a room to decay by 60 dB.
Tip: The humidity can have a significant impact on the
absorption of sound at high frequencies. The impact is largest
at low to medium humidities, with a peak around 20%.
How to C#: Basic SDK Concept of XDoc.PDF for .NET XDoc.PDF for .NET allows C# developers to edit hyperlink of PDF document, including editing PDF url links and quick navigation link in bookmark/outline.
add page number to pdf hyperlink; clickable pdf links VB.NET PDF: Basic SDK Concept of XDoc.PDF XDoc.PDF for .NET allows VB.NET developers to edit hyperlink of PDF document, including editing PDF url links and quick navigation link in bookmark/outline.
adding an email link to a pdf; adding links to pdf
23
Bose
®
Modeler
®
6.5 Software Tutorial
Chapter 5: Predicting Sound 83
For this model, we will set the first three parameters as follows:
Setting the Background Noise
Selecting the curve
We will now set the Background Noise:
1. Click on the Background Noise Open button.
Figure 5.2 - Background Noise, Open button
The following window appears:
Figure 5.3 - Background Noise window
Temperature:
22
o
C
Humidity:
40%
Occupancy:
0 (We start by looking at the sound system
when the room is empty).
32
Bose
®
Modeler
®
6.5 Software Tutorial
84 Chapter 5: Predicting Sound
In this window, you can either use one of the predefined noise
curves, or if you have actual measurements from the space, simply
create your own noise files.
Click on a few of the different noise files to get familiar with the
format. You can duplicate files, rename them and delete some of
them.
Creating your own Background Noise
For this example, we have measured the actual background noise
in a room. We will now create a custom noise file with this data:
1. Click on the New Noise Curve button (or select New from the
File menu).
Figure 5.4 - New Noise Curve button
Note: Background noise can have a significant impact on
predictors such as speech intelligibility and echoes.
Background noise can reduce intelligibility. Plus, it can help
mask a late strong reflection that may otherwise have appeared
as an echo.
Note: The standard files (NCB - Balanced Noise Criteria
a
) and
RC (Room Criteria
a
) are predefined and locked. They cannot be
changed unless you duplicate them first..
a. See American National Standard Criteria for Evaluation Room Noise
ANSI S12.2-1995 (ASA 115-1995).
11
Bose
®
Modeler
®
6.5 Software Tutorial
Chapter 5: Predicting Sound 85
2. Name the file “Noise_Church”, then click on OK.
Figure 5.5 - Adding a New Noise Curve
The file appears at the route of the acoustics data folder:
3. Select the Noise_Church file by clicking on it.
Figure 5.6 - New Noise Curve file
23
Bose
®
Modeler
®
6.5 Software Tutorial
86 Chapter 5: Predicting Sound
4. Select 1 octave band for the bandwidth.
Figure 5.7 - New Noise Curve file with 1 Octave selected in Bandwidth
Note: Storing a Gain Offset for the Background Noise File.
In some cases you may need to increase or decrease the gain
of a background noise file. One possible way to do this is to
create multiple copies with different levels.
Modeler provides an easier way by using a Gain Offset function
that allows you to specify a gain offset per room model.
To access the Gain Offset function, open the Background Noise
Database, and preview the background noise file using the
steps described earlier. While previewing the background noise
file, you can use the Gain Offset function to increase or
decrease the initial level of the background noise.
A Gain Offset can be defined for each room model where this
particular background noise file is used. The Gain Offset
information is stored with the room model, and is recalled the
next time the room model is opened.
19
Bose
®
Modeler
®
6.5 Software Tutorial
Chapter 5: Predicting Sound 87
5. Enter the numbers as follows:
Figure 5.8 - Added numbers for New Noise Curve file
We now have entered the background noise.
6. Click on OK. You will then return to the Acoustic tab. You will
see the name Noise_Church in the Background Noise
section.
Figure 5.9 - Noise_Church in Background Noise field
Tip: To clear a previously selected background noise file:
•
Simply replace it with another background noise file.
Note that there is a file “No Noise (-30 dB)”. When this file is
selected, the room model is simulated with no background
noise.
16
Bose
®
Modeler
®
6.5 Software Tutorial
88 Chapter 5: Predicting Sound
Setting the House Curve
By setting the House Curve, you may quickly modify the rooms
average response to match your preferred shape (House Curve).
We will now set the House Curve.
1. Click on the House Curve Open button.
Figure 5.10 - House Curve, Open button
The following window appears:
Figure 5.11 - House Curve window
This window works similarly to the Background Noise window.
Click around to get familiar with the functionality.
16
Bose
®
Modeler
®
6.5 Software Tutorial
Chapter 5: Predicting Sound 89
2. Select the curve labelled Flat_w_4k_knee, which is flat to 4 kHz,
and then rolls off by 3 dB per octave band.
Figure 5.12 - House Curve
3. Click on OK, and you will return to the Acoustics tab. Notice
that the House Curve name appears in the House Curve section.
Figure 5.13 - Acoustics tab, showing House Curve name
For information on Matching RT
60
, see Matching reverberation
times, on page 283 of the Advanced Topics chapter.
29
Bose
®
Modeler
®
6.5 Software Tutorial
90 Chapter 5: Predicting Sound
Setting the occupancy level
Finally we will set the occupancy level of the environment.
1. In the Occupancy section, click the radio button next to Percent
Full.
2. Enter 90 in the Percent Full field of the Acoustics tab.
Figure 5.14 - Acoustics tab, occupancy conditions
Note: If you have measured reverberation times for the existing
space, Modeler has an algorithm that allows you to match
measured with predicted reverberation times for improved
prediction accuracy. For more information, see Matching
reverberation times, on page 283.
Tip: To specify the occupancy conditions of the room, at least
one surface must be designated as occupied. If you find the
Percent Full field grayed out in the Acoustics dialog box, follow
these steps to designate the seating surfaces as Occupied:
•
Click the Surfaces tab in the Detail window.
•
Right-click in the window and go to Sort > By Type.
•
Find the Seating1 surfaces and in the Audience
column, change the value to Occupied for each
surface.
Documents you may be interested
Documents you may be interested
