Vuvuzela sound measurements

Abstract

1 reported the maximum output levels of a vuvuzela at various distances from the horn. In response to enquiries, we provide additional information on the method and results reported in the earlier paper.One commercial vuvuzela was used in the recording of sound levels at 4 different positions: (i) at the ear of the person blowing the vuvuzela; (ii) at the bell end; (iii) 1 m from the bell end; and (iv) 2 m from the bell end. All measurements were made approximately 1.6 m from the ground, in an openair setting. Sound levels were measured twice at a single instance while the vuvuzela was being blown by one of the investigators. Measurements were made using a calibrated Type 1 Larson Davis SLM 824 sound level meter with a 2559 normal sensitivity microphone fitted with a manufacturersupplied windscreen (WS001). Measurements were made using the fast response time option, which corresponds to a time constant of 0.125 s that is intended to approximate the time constant of human hearing. for measuring individual sound events. A-weighting was used for all measurements to compensate for the non-linear sensitivity of the human ear, which is differentially sensitive to sound across the frequency spectrum (least sensitive at very high and very low frequencies). A breakdown of the average intensities at individual frequencies across the frequency spectrum is provided in Table I. A characteristically flat frequency spectrum was evident between 250 and 8 000 Hz. The average intensity difference between the individual frequency measurements (Table I) of the 2 recordings at each of the 4 respective distances from the bell of the vuvuzela was 0.6 dB (±3.2 dB standard deviation).These measures provide an indication of the sound levels and frequency spectrum of a typical vuvuzela. There are now numerous types of vuvuzela made by several manufacturers, which may all produce varying intensity and frequency outputs. In addition to these variables, individuals blowing a vuvuzela will produce varying intensities depending on their technique and the pressure exerted. Also, the sound level produced by multiple individuals simultaneously blowing vuvuzelas within a limited space cannot be predicted from these data.

Wool Dyeing—A Path to Progress

“…A further improvement in this technique has been suggested by CSRIO (9). Since milling acid dyes show little migration during boiling, there is no need to use a prolonged heat treatment once a level strike has been achieved.…”

Propagation of Respiratory Aerosols by the Vuvuzela

“…They have been banned from a number of sports grounds due to the volume of noise emitted and safety concerns arising from their ability to nullify public address systems. Studies have previously suggested that vuvuzela playing poses a risk of noise induced hearing loss [37] , [38] . We recommend that consideration is taken of their propensity to disseminate respiratory aerosols and that persons with respiratory infections be advised not to blow their vuvuzela in places where they risk infecting others.…”

Spectral optoelectronic features of Cu-containing arsenic sulfide (As2S3)0.95Cu0.05

“…n 0 ) 3 (n ? n s 2 ), C = 2(n 2 -n 0 ) (n 2 -n s 2 ), D = (n -n 0 ) 3 (n -n s 2 ), u = 4pnd/k and x is the absorbance that is given by x = exp(-ad).The idea of creating envelopes in the interference zone, proposed by Manifacier et al [25], has been developed by Swanepoel [18,19] to determine the thickness of a homogeneous thin film form the Ch-Gs materials (Inset of Fig. 1 shows the envelopes of the interference maxima and minima).…”

“…The thickness of the (As 2 S 3 ) 0.95 Cu 0.05 film was calculated based on the envelopes of the transmission spectrum using the Swanepoel Theory [18,19]. The envelope technique enabled the determination of the average thickness and the refractive index of the Ch-Gs films with accuracy better than 1% [20].…”