MAE - McIntosh Applied Engineering, LLC

MAE instructional videos



Ares Acoustic System Videos

Introduction to Ares Short video providing a brief introduction to the Ares Acoustical System used to design audio products such as cellphones, tablets, headsets, etc. It discusses the modular approach of the Ares interface, how to create modules, the function of the current modules, how to access these instructional videos and the module manuals. Installing Ares on a Windows PC Machine This video provides instructions on how to obtain the Ares installation files and takes you through the installation process. Some common installation problems are discussed. Using the local license feature This video shows how to use the Ares offline license feature that allows you to keep a license checked out to your local computer so you don't have to have internet access to use Ares. When this feature is used, the license cannot be used by any other computer. Using Cursors in Ares Graphs Cursors allow you to pick specific data points off of a graph and perform some simple processing of the graph data such as computing the slope, finding maximum and minimum values, and curve fitting polynomial functions to the data. They can be created in any Ares graph and so are a generic tool for the Ares development system. The difference between two cursors can be displayed which is useful for finding 3 dB down points and reporting on the difference between two curves.

Acoustic Modeler Videos

Modeling of a Simple Loudspeaker Enclosure Short video showing how to build a simple loudspeaker model with a rear volume and a radiating front surface. Topics include basic loudspeaker behavior, importing Thiele-Small parameters, and plotting electrical impedance. Acoustic Microphone Modeling Short video showing how to build a simple ported microphone model as one may see in a cellphone or tablet. Topics include front port Helmholtz resonance, using graph buffers, effects of acoustic cloths to keep out foreign material, and exporting model parameters to the clipboard. Introduction to Ear Simulators and their use in the Ares Acoustic Modeler An introduction to ear simulators used in the telephony and audio industries, including mechanical "ears" and "real pinna" ears used on head and torso simulators (HATS). A description of how the Ares Acoustic Modeler handles these simulators are given as well as examples of how to use the simulators. One limitation of ear simulators is in capturing the behavior of devices which go into an ear canal. The IEC-711 or ITU Type 2 ear simulator is designed to model the effects of audio devices which drive the entrance of the ear canal, but not devices which are inserted into the canal. Ares can be used to overcome this limitation and model the effects of inserting devices into the ear canal. This is done through the uses of ports with negative lengths. A discussion of how to do this starts at 39:00. Prior to the December 20, 2016 release of Ares version 1.400, there was an error in the IEC-711's ERP to DRP transfer function. This has been corrected. This error is discussed at 49:50 in the video. An example of how to create your own "custom ear simulator model" is discussed at 52:40. Custom ear simulators are important when your audio device interacts with an ear in ways that the original ear simulators weren't designed to capture. NOTE: This video says that the lower left node of the Ear Simulator element produces an equivalent HATS diffuse field pressure that would generate the DRP pressure. However, since this video was made, an option has been added to allow you to select this node to produce the equivalent diffuse or free field HATS pressure, not just the diffuse field pressure. Using a the graph element in the Acoustic Modeler Lengthy video going through all of the features in the Modeler's graph element. Topics include using graph buffers, plotting pressure, velocity, displacement, impedance, electrical quantities. Plotting magnitude, real and imaginary parts, phase, linear vs dB values, octave plotting, as well as metrics as well as: average level, speech weighting, Zwicker loudness (Sone/Phon), RLR, and SLR. Applying A, B, C, ITU P.50 speech, and psophometric weightings. Importing and exporting data and using response masks. Plotting and Exporting Impedance Data From the Ares Acoustic Modeler Short video showing how to plot and export impedance data from a headset model using the graph element. Introduction to Acoustically Modeling Porous Material in Ares Introduction to the physical effects of porous material on the acoustic process, the porous material modeler in Ares, and an example of using it in the modeler. Some of the applications of porous materials is in increasing the effective volume of a speaker cabinet and adding damping to long port being used as a waveguide. Using Knowles and Sonion elements in Ares Acoustic Modeler This video provides a brief introduction to using Knowles Electronics and Sonion Corporation's microphone and speaker/receiver elements. Microphone Modeling using Sensitivity and Impedance Tables This video shows how to model an omni microphone using complex frequency dependent sensitivity and acoustical impedance lookup tables. The acoustical resistor, acoustical transfer function, and omni microphone are used to model the complex behavior. The lookup tables can be supplied by the microphone vendors.

Nonlinear Acoustic Modeler

Introduction to the Nonlinear Acoustic Modeler This video provides an introduction to the Nonlinear Acoustic Modeler. This modeler predicts the THD from small "speaker boxes" found in most cell phones and tablets. The modeler captures the nonlinear behavior of a moving coil loud speaker and the nonlinear behavior of materials typically used to cover the acoustic ports to produce acoustic damping and keep out foreign material. The effects of drive level, material choice and design geometry can be seen on the predicted THD. The model can also process a WAV file so listening tests can be performed.

Frequency Response Measurement

Introduction to the Frequency Response Measurement Module The Frequency Response Module uses a 2 channel sound card to perform frequency response measurements on acoustical systems. Typically these consist of transfer functions between two microphones or drive speaker voltage and microphone. Power spectrum, THD, and SNR are also measured. Stepped sine and chirp provide pure sine wave measurements, but there is also the ability to use arbitrary waveforms from a WAV file. This latter usually consists of using a speech WAV file to measure the response of a DSP system which performs complicated nonlinear processing (such as noise reduction) which are commonly not easily measured with pure tones. Tools for computing telephony metrics are provided. These include SLR (Send Loudness Rating), RLR (Receive Loudness Rating), TCLw (weighted Terminal Coupling Loss), STMR (Side Tone Masking Rating), and channel noise. A "math buffer" feature allows for complex math operations on the measurements to be performed on the measured data without having to export the data to other programs.

Using Math Buffers to process data in the Frequency Response Measurement module Math buffers in the Ares Frequency Response module allow for manipulation of the data within the Ares environment without having to export the data to a program like Excel or Matlab. This video take you through applying the math buffers, and shows their use in three examples. One is showing the differences in measurements when there are small changes made in the acoustical environment, such as putting an acoustic material over a speaker. The second is showing how the electrical impedance into a speaker can be computed from a measurement made with a resistor placed in series with the speaker. And the third shows how the particle velocity out of an acoustic port can be estimated using a simple source approximation. (Particle velocity is important to know so you can avoid nonlinear jetting at high amplitudes.)

Flow Impedance Measurement Apparatus

Acoustic Flow Impedance Measurement of Thin Material Video showing how the MAE100 flow impedance apparatus can be used to measure the impedance of a thin woven material and how that impedance can be imported into the Ares acoustic modeler. Flow Impedance Sound Card Calibration Shows the sound card calibration process for Ares' Flow Impedance Measurement Apparatus module. The calibration consists of two parts. The first is to determine the sound card's maximum input voltage, and the second is to measure the excess transfer function between the left and right input channels. Either of these steps can be skipped if the current calibration data is not to be replaced. Sound card calibration data is automatically saved to the Ares.cfg file upon exit and will be reloaded the next time Ares is run. However, it is recommend to export the calibration data to a dedicated cal file which can be loaded at a later time. MAE103 Flow Impedance Calibration and Measurement The MAE103 works with the Flow Impedance Measurement module to measure the flow impedance of small acoustic parts, typically between 1 and 3 mm in diameter. Parts this small generally have a much higher impedance than the MAE100 apparatus can measure, so the MAE103 was designed to measure the large impedance found in these small parts. This video covers the calibration of the MAE103 apparatus and provides a measurement example.

Surface Impedance Measurement Apparatus (SIMA)

NOTE: There is an issue with the current SIMA devices where the built in ASUS U7 sound card doesn't enumerate properly. It appears to have problems working from a USB port other than the original port that it was plugged into when the SIMA device was initially installed. If Ares can't find a SIMA device because the sound card hasn't enumerated, try plugging the SIMA device into the original USB port that was used when the SIMA device was first used. Acoustic Impedance Measurement Lengthy video showing the SIMA (Surface Impedance Measurement Apparatus). Shows the SIMA case, connecting the system, calibrating the measurement devices, measuring the impedance into a simple volume, effects of adding acoustic damping material to the volume, importing the data into the Acoustic Modeler and using it to demonstrate the effects of rear volume modes on a speaker's response. Acoustic Impedance Measurement (w/o calibration) Shorter version of above video but with the calibration sequence removed ro reduce the playing time by 5 minutes. Using Acoustic Impedance to Detect a Leak Around a Microphone Video showing how the SIMA device can be used to detect very small leaks. In this case, the leak is between a surface mount MEMS microphone and a flex circuit. Shows how the size of the leak can be quantified and the gap size estimated. Measuring the Acoustical Properties of Porous Material using SIMA This video show how to measure the acoustical parameters for a rigid frame porous material using the Ares SIMA device and the acoustic modeler. Parameters for four materials were measured: 3 lbs/cf cotton, 3 lbs/cf rigid Owens Corning fiberglass fiberboard, 4.3mm steel shot, and two densities of polyester batting. Good correlation between the acoustical impedance into the materials and the model were achieved. The use and merits of acoustic porous material is discussed.

Coordinate Mapper

Introduction to the Coordinate Mapper Module The Coordinate Mapper module is a simple tool which aids you to obtain coordinates from bitmap images. These images are usually a graph which has a curve that you want to digitize. It can also be an image of a mechanical structure that you want to obtain coordinate data from when it's not convenient to simply measure the locations or dimensions with a caliper. This video shows how to use the module and provides an example of getting the data off of a Head And Torso Simulator (HATS) curve and pasting it into a Modeler graph element. It also shows how to accurately obtain the location of ultrasonic microphones on a printed circuit board.

Hardware

MAE206 Microphone Amplifier The MAE206 is a two channel signal and microphone amplifier meant to work with analog sound cards. The left and right channels can independently be set to: amplify from -20 to 40 dB in 6 dB steps, frequency range from 20 Hz to 20kHz, provide independent and phantom power to analog microphones, and produce a 1kHz 100 mV peak-to-base sine wave for sound card calibration. The amplifier is controlled from a Windows PC application through a USB connection. (There are no controls on the amplifier panels.) The discrete amplifier steps allow for accurate measurement capability.