By changing the shape of the mouth, the frequency response of the filter is changed, so removing ( subtracting ) some of the harmonics.

The vocal tract ( the throat and mouth ) forms the tube, which is characterized by its resonances, which give rise to formants, or enhanced frequency bands in the sound produced.

Some horn designs not only fold the low frequency horn, but use the walls in a room corner as an extension of the horn mouth.

It emits echolocation sounds through the mouth like Myotis daubentoni, but the sounds are quite different, containing a long constant frequency part around 55 kHz, which is an unusually high frequency for a bat this large.

For example, in a study of the Eastern Chongming Island and Jiuduansha Island tidal marshes at the mouth of the Yangtze River, China, the amount of sediment adhering to the species Spartina alterniflora, Phragmites australis, and Scirpus mariqueter decreased with distance from the highest levels of suspended sediment concentrations ( found at the marsh edge bordering tidal creeks or the mudflats ); decreased with those species at the highest elevations, which experienced the lowest frequency and depth of tidal inundations ; and increased with increasing plant biomass.

This unique type of singing involves the production of two distinctively audible pitches at the same time, including a low pedal note, or drone, derived from the fundamental frequency of the vocal cord vibrations, and higher melodic notes that result when the singer's mouth acts as a filter, selecting one note at a time from among the drone's natural overtone series pitches.

In addition to the nose and mouth, the vocal cords and lungs also make a contribution to producing speech by controlling the volume ( amplitude ) and pitch ( frequency ) of the sound.

The flare rate and the mouth size determine the low frequency limit.

A common solution is to use two or more horns, each with the appropriate throat size, mouth size and flare rate for best performance in a selected frequency range, with sufficient overlap between the frequency ranges to provide a smooth transition between horns.

The size of the tractrix horn is generated by specifying the desired low frequency " cutoff " or limit which will determine the mouth diameter.

Keele's paper set forth the relationships between mouth size, frequency and coverage angle, providing a basis for many future developments of horn design.

The Model-C and-M horns required stacking in groups of four, increasing effective horn mouth size to achieve the low frequency target.

A technique for obtaining an estimate of the glottal volume velocity waveform during voiced speech is the “ inverse-filtering ” of either the radiated acoustic waveform, as measured by a microphone having a good low frequency response, or the volume velocity at the mouth, as measured by a pneumotachograph at the mouth having a linear response, little speech distortion, and a response time of under approximately 1 / 2 ms. A pneumotachograph having these properties was first described by Rothenberg and termed by him a circumferentially vented mask or CV mask.

A whistle has a characteristic natural resonant frequency that can be detected by gently blowing human breath across the whistle rim, much as one might blow over the mouth of a bottle.

When a whistle is sounding its natural frequency, the effective length referred to here is somewhat longer than the physical length above the mouth if the whistle is of uniform cross-sectional area.

Formulas are available to estimate the effective length of a whistle, but an accurate formula to predict sounding frequency would have to incorporate whistle length, scale, gas flow rate, mouth height, and mouth wall area ( see below ).

* Mouth arc – The natural frequency of a whistle with a 360-degree mouth ( that extends completely around the whistle circumference ) is lower than that of a whistle of the same length and same mouth area but with a partially walled mouth, resembling an organ pipe.

Transcutaneous electrical nerve stimulation ( TENS ) and interferential current ( IFC ) use a painless electric current and the physiological effects from low frequency electrical stimulation to relieve stiffness, improve mobility, relieve neuropathic pain, reduce oedema, and heal resistant foot ulcers.

João Dinis de Sousa, Viktor Müller, Philippe Lemey, and Anne-Mieke Vandamme proposed that HIV became epidemic through sexual serial transmission, in nascent colonial cities, helped by a high frequency of genital ulcers, caused by genital ulcer diseases ( GUD ).

With some applications, how the phase varies with frequency can be a significant consideration.

The filter response can also be completely characterized in the frequency domain by its transfer function, which is the Fourier transform of the impulse response h. Typical filter design goals are to realize a particular frequency response, that is, the magnitude of the transfer function ; the importance of the phase of the transfer function varies according to the application, inasmuch as the shape of a waveform can be distorted to a greater or lesser extent in the process of achieving a desired ( amplitude ) response in the frequency domain.

In particular, the pitch of calls varies, with larger species producing deeper sounds ; overall, the frequency of felid calls ranges between 50 – 10, 000 hertz.

The segment of the radio frequency spectrum used by 802. 11 varies between countries.

Without referral to an aether, this physical interpretation of relativistic effects was shared by Kennedy and Thorndike in 1932 as they concluded that the interferometer's arm contracts and also the frequency of its light source " very nearly " varies in the way required by relativity.

The operating frequency varies with changes in load impedance, with changes in the supply current, and with the temperature of the tube.

When the frequency of an event varies as a power of some attribute of that event ( e. g. its size ), the frequency is said to follow a power law.

Otherwise, when the phase velocity varies with frequency, velocities differ and the medium is called dispersive.

When a beam of white light passes from air into a material having an index of refraction that varies with frequency, a phenomenon known as dispersion occurs, in which different coloured components of the white light are refracted at different angles, i. e., they bend by different amounts at the interface, so that they become separated.

Powered by the line, the microphone ( A2 ) produces a modulated electrical current which varies its frequency and amplitude in response to the sound waves arriving at its diaphragm.

To model dispersive wave phenomena, those in which the speed of wave propagation varies with the frequency of the wave, the constant c is replaced by the phase velocity:

Bamboos seldom and unpredictably flower, and the frequency of flowering varies greatly from species to species.

If F is a linear function, for instance a filter whose gain and / or delay varies with frequency, then the signal will experience linear distortion.

In a waveguide, propagation velocity varies with frequency.

An electro-optic effect is a change in the optical properties of a material in response to an electric field that varies slowly compared with the frequency of light.

The ionization of the atmosphere varies with time of day and season as well as with solar conditions, so the upper frequency limit for skywave communication varies on an hourly basis.

The speckle effect is a result of the interference of many waves of the same frequency, having different phases and amplitudes, which add together to give a resultant wave whose amplitude, and therefore intensity, varies randomly.

When we observe an illuminated surface, we detect the average energy of the light at the surface ; thus the brightness of a given point on a surface which has been illuminated by a set of random scatterers with a single frequency, is constant over time, but varies randomly from point to point, i. e. it is a speckle pattern.

The impedance of the antenna varies based on many factors including: the antenna's natural resonance at the frequency being transmitted, the antenna's height above the ground, and the size of the conductors used to construct the antenna.

Sophisticated pitch generators will also include sweep generators ( a function which varies the output frequency over a range, in order to make frequency-domain measurements ), multipitch generators ( which output several pitches simultaneously, and are used to check for intermodulation distortion and other non-linear effects ), and tone bursts ( used to measure response to transients ).

The frequency of donations varies among countries.

By this standard, it is determined that where two stations operating on the same frequency are involved, objectionable interference from station A exists at any point within the service area of station B where station A's signal is of an intensity one-twentieth or more of the strength of station B's signal at that point.

The effect of the recording is very open and natural, with the frequency emphasis exactly what you would expect from a live performance.

The effect is that the platform returns from an off-level position at a rapid rate until it is nearly level, at which point the platform is controlled by a proportional servo with low enough frequency response so that the noise has little effect on the leveling process.

`` However, evidence that the Axis powers are making significant preparations indicative of such an intention is being reported with increasing frequency from a variety of sources.

Moseley, after discussions with Bohr who was at the same lab ( and who had used Van den Broek's hypothesis in his Bohr model of the atom ), decided to test Van den Broek and Bohr's hypothesis directly, by seeing if spectral lines emitted from excited atoms fit the Bohr theory's demand that the frequency of the spectral lines be proportional to a measure of the square of Z.

The square root of the frequency of these photons ( x-rays ) increased from one target to the next in a linear fashion.

While current mouthwash treatments must be used with a degree of frequency to prevent this bacteria from regrowing, future treatments could provide a viable long term solution.

Observation of electron tracks independent of the frequency of the incident photon suggested a mechanism for electron ionization that was caused from an internal conversion of energy from a radiationless transition.

A channel actually consists of two signals: the picture information is transmitted using amplitude modulation on one frequency, and the sound is transmitted with frequency modulation at a frequency at a fixed offset ( typically 4. 5 to 6 MHz ) from the picture signal.

The age of the patient and the frequency with which BCG is given has always varied from country to country.

Bayesian probability interprets the concept of probability as " an abstract concept, a quantity that we assign theoretically, for the purpose of representing a state of knowledge, or that we calculate from previously assigned probabilities ," in contrast to interpreting it as a frequency or " propensity " of some phenomenon.

In the " Question and Answer " section of his website, Brooks explains that the " Double Quarter-Pounder with Cheese " meal from McDonald's possesses a special " base frequency " and that he thus recommends it as occasional food for beginning breatharians.

He became the most famous film star in the world before the end of World War I. Chaplin used mime, slapstick and other visual comedy routines, and continued well into the era of the talkies, though his films decreased in frequency from the end of the 1920s.

It operates on a frequency varying from daily to thrice weekly on inter-island flights to each of the seven islands with operational airports and also to Dakar.

Rodolfo Llinás, for example, proposed that consciousness results from recurrent thalamo-cortical resonance where the specific thalamocortical systems ( content ) and the non-specific ( centromedial thalamus ) thalamocortical systems ( context ) interact in the gamma band frequency via temporal coincidence.

In 1967, a specific frequency from the emission spectrum of caesium-133 was chosen to be used in the definition of the second by the International System of Units.

Also in 1877, he proposed measuring the meter as so many wavelengths of light of a certain frequency, the kind of definition employed from 1960 to 1983.

Electrons can also be emitted from the electrodes of certain metals when light of frequency greater than the threshold frequency falls on it.

The system analysis is carried out in time domain using differential equations, in complex-s domain with Laplace transform or in frequency domain by transforming from the complex-s domain.

Here the light signal from the fiber is translated to a radio frequency electrical signal, which is distributed through coaxial cable to individual subscriber homes.

While there were some papers from before that time, this collection documented an entire variety of finished, working audio coders, nearly all of them using perceptual ( i. e. masking ) techniques and some kind of frequency analysis and back-end noiseless coding.