This paper describes the long-term noise monitoring data for ten consecutive years (2011–2020) acquired from the diversified National Ambient Noise Monitoring Network (NANMN) set up across 7 major cities of India and consisting of 70 stations for continuous noise monitoring throughout the year. The annual average ambient noise levels observed throughout these ten years in 70 locations under study, including 25 locations in commercial zones, 12 in industrial, 16 in residential, and 17 in silence zones, are described. The noise scenario in these ten years is compared and analyzed. It is observed that no site in residential or silence zones meets the ambient noise limits for the past ten years. The study suggests guidelines for a policy framework for environmental noise management and control to regulate noise pollution in Indian cities.

Toys emitting sounds are classified as significant sources of noise found in the children environment. Impulse and continuous noise emitted by toys, used in close to the child’s ear, acting directly on the organ of hearing, can lead to serious adverse health effects. This is especially true for children under the age of three, in which the state of the hearing organ determines their intellectual development. The current level of safety of sound emitting toys intended for children in this age group is insufficient. This is confirmed by the reports from the control of market surveillance authorities. A new approach to the assessment of children’s exposure to noise generated by toys, included in EN 71-1:2011 + A2:2013 Standard, based on the permissible values applicable to the workplaces, requires further tests and verification. The paper presents the results of the research work and assesses the level of sound emitted by toys in the light of current standard requirements, carried out using the author’s methodology. Toys intended for children under the age of 3 years, commercialized on the European market by Polish manufacturers and importers were tested. The results of the tests allowed us to determine the impact of duration of the sound pressure level measurement on the final result.

The paper analyzes the monthly day equivalent levels, Lday (06–22 h) and night equivalent levels, Lnight (22–06 h) values observed in year 2015 and 2016 for the 70 locations whereby continuous noise monitoring is conducted under the National Ambient Noise Monitoring Network (NANMN). The study exclusively analyzes the ambient noise data acquired for 25 locations in commercial zone, 12 in industrial, 16 in residential and 17 in silence zones. The analysis of (Lday–Lnight) for 70 locations under observations reveals that 10 dB night time adjustment in day-night average sound level descriptor is not appropriate in such a scenario and as such it is recommended to use day-night average sound level and day-eveningnight average sound level descriptors without any 10 dB night time adjustment or 5 dB evening time adjustments. The analysis and conclusions of the present study shall be very useful for developing single value noise descriptor correlating the noise annoyance and health effects in Indian perspectives.

Noise mapping is based on long-term noise indicators, such as L _N or L _DEN. On the other hand, transportation intensity changes during a day (road traffic peak hours) or a year (more flights during holidays) and this variability is not reflected in single sound level values. We wanted to find out whether not only sound level but also the number of noise events is the factor influencing noise annoyance assessment. Ambisonic recordings of real traffic in a city were used. Road, tramway, and aircraft traffic were investigated and two factors were manipulated: the equivalent sound level value and the number of noise events. All stimuli were presented in an anechoic chamber. The results showed that sound level is always a statistically significant parameter while the number of events has an impact only for tramways and airplanes. Moreover, the difference is observed only between one or more subgroups, no matter what the sound level value was. For road traffic this relation was not found to be statistically significant. It was also shown that the existence of tramway bonus or airplane malus is linked with the number of noise events.

As a consequence of recent implementations of EU Directives related to noise protection more and more students of various AGH-UST programs are introduced to the basics of acoustic measurements. Students at various levels of theoretical background in the field of acoustic measurements are offered practical training in measurements using digital sound analyzers. The situation would be optimal if each student could have a device at his/her own disposal. Unfortunately, such a situation is not possible at the moment because of various reasons.

With the above problem in mind, a dedicated software package has been developed, implemented in the LabVIEW environment, which allows detailed studies of problems related to the acoustic signal measurement using sound level meters, as well as tasks in spectral analysis (1/1 and 1/3 band filters) and narrow-band (FFT) analysis. With such organization during the introductory laboratory classes each student is offered a direct individual contact with a virtual device that is properly pre-programmed for realization of a well-constructed learning process. It definitely facilitates understanding of the essence of acoustic signal measurements and provides a good basis for further laboratory work carried out as a team-activity.

The condition monitoring techniques like acoustic emission, vibration analysis, and infrared thermography, used for the failure diagnosis of bearings, require longer processing time, as they have to perform acoustical measurement followed by signal processing and further analysis using special software. However, for any bearing, its period of usage can be easily determined within an hour, by measuring the bearing sound, using sound level meter (SLM). In this paper the acoustical analysis of the spindle bearing of a radial drilling machine was performed using SLM, by measuring the sound pressure level of the bearing in decibels, for different frequencies, while muting all the other noises. Then using an experimental set up, two database readings were taken, one for new bearing and the other for completely damaged bearing, both are SKF6207, which itself is the spindle bearing. From these three sets of sound pressure level readings, the period of usage of the spindle bearing, was calculated using an interpolation equation, by substituting the life of the bearing from the manufacturer’s catalogue. Therefore, for any machine with a SKF6207 bearing, its usage time can be estimated using the database readings and one measurement on that machine, all with the same speed.