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Product Noise Control

Course No. 198

(Course Outline shown below.)

Applications This course provides an introduction to the physics, principles, language and fundamental techniques used to control noise. Emphasis will be placed on the practical applications of the physical principles behind noise control.

For whom intended The course is intended for technicians who work in sound control testing and engineers who have recently been assigned responsibility for product noise control. Upon completion of the course, the participant will be able to choose the appropriate noise control mechanism (absorption, barriers, source modification) and avoid the costly over-application of noise control materials which is common in retrofit programs. The course will also be beneficial for engineering managers who must evaluate the noise control programs within their area of responsibility.

Brief course description A short introduction will be given to subjective measures of noise which serve as the background for many of the noise measurement methods in common use. The control of existing product noise through the design of enclosures and barriers will be covered. This course will also include a discussion of the design and qualifications of anechoic rooms, reverberant rooms and outdoor test sites.

While the course is developed for participants from the automotive industry — manufacturers, OEM companies and supplier companies responsible for automotive noise control treatments — the material will also be applicable to personnel from other industries. Examples and case studies from automobile applications and various heavy duty vehicle applications will be discussed if time permits.

The material presented will be practical in nature with mathematics limited as much as possible.

Certificate Programs This course is required for TTi’s Mechanical Design Specialist (MDS) certificate program. It may be used as an elective for any other TTi specialist certificate program.

Prerequisites There are no formal prerequisites for this course. Supervisors are invited to contact TTi on prospective attendees' backgrounds and needs.

Text Each student will receive a course workbook, including most of the viewgraphs used in the course presentation.

Course Hours, Certificate and CEUs Open courses meet seven hours per day. Upcoming presentation dates can be found on our current open course schedule. Class hours/days for on-site courses can vary from 14-35 hours over 2-5 days as requested by our clients. Upon successful course completion, each participant receives a certificate of completion and one Continuing Education Unit (CEU) for every ten class hours.

Course Outline No. 198

Introduction to Noise
- The Nature of Sound
- Acoustic Measurements and Terminology
  - Propagation Velocity
  - Pressure
  - Sound intensity
  - Impedance
  - Frequency and Wavelength
  - Use of Decibels
- Sound Pressure Level (SPL), Sound Power Level (PWL)
- Adding, subtracting, averaging SPL or PWL
- Spreading of Sound Waves
- Sound Level Variation
- Directivity Index
- Doppler Effect
Basic Noise Control Concepts
- Absorption of Sound
- Absorption vs. Thickness
- Membrane Coverings
- Perforated Metals
- Absorption
- Reverberation
- Barriers
- Enclosures
- Absorption vs. Damping; Damping vs. Isolating
Basic Concepts in Noise and Vibration
- Sound Perception
- Terms
- Loudness Perception
- Fletcher Munson Curves
- Noise Criteria (NC) Curves
- Noise Rating (NR) Curves
- Stevens Method
- Vibration Basics
  - Sine Wave
  - RMS Values
  - SDoF Systems
  - Harmonic Waves
  - Radians
  - Natural Frequency (Resonance)
  - Transmissibility
  - Isolation
  - Damping
- Critical Frequencies
- Structural Propagation — Rods
Noise Measurement: Instrumentation
- Microphones
- Definitions of Terms
  - Free field
  - Free Field Response
  - Pressure Response
  - Diffuse Field (Random Incidence)
  - Free-Field and Random-Incidence Corrections
- Reverberant Rooms
- Capacitor Microphones
- Electret Microphone
- Dynamic Range
- Frequency Range
- Moving-Coil or Dynamic Microphone
- Piezoelectric Microphones
  - Direct Piezoelectric Effect
  - Ceramic Systems
- Microphone Calibration:
  - Reciprocity
  - Closed Chamber
- Microphone Windscreens
- Sound Level Meters (SLM)
- Weighting Curves
- Detectors
Vibration Instrumentation
- Use of Accelerometers:
  - Basic Principles, Bridge Type, Piezoelectric Type
  - Calibration
  - Mounting
  - Selection and Care, Limitations
Spectrum Analysis
- Spectrum Analyzer
- Parallel Filter Analyzer
- Filters
- Time-Compression Analyzers
- FFT Analyzers
- Fourier Transforms
- Resolution
- Windows
- Ripple
- Aliasing
- Bandwidth
- Cross Spectrum
- Transfer Functions
- Coherence
Data Capture and Analysis
- Magnetic Tape Recording
- FM Principle
- Frequency Division Multiplexing
- Digital Audio Tape (DAT) Recorders
- Signal Sources
- Sampling Frequency
- Filtering and Oversampling
- Analog-Digital Conversion
Design of Facilities: Reverberent Rooms
- Anechoic and Hemi-anechoic Rooms
- Outdoor Sites
- Dynamometers
  - Eddy Current
  - Hydrokinetic
- Existing Standards
Testing Acoustical Materials
- Acoustic Materials Standards
  - Absorption: ASTM C 423, ASTM C 384, ASTM B 1050
  - Barriers: ASTM E 90, SAE J 1400
  - Damping: ASTM E 756, SAE J 1637
Quiet Design for Automotive Applications: Noise Control Materials
- Typical Absorbers and Barriers in Vehicles
- Sources of Noise in Vehicles
  - Tires
  - Road
  - Wind
  - Accessories
- Seals and Leaks
- Interior Vehicle Modes
Summary
Final Exam
Award of Certificates for successful completion

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