"The tempered scale and the natural scale should be rejected. In Egypt, the Egyptian scale is to be kept with the values, which were measured with all possible precision. The Turkish, Syrian, and Iraqi scales should remain what they are...." Both in modern practice, and evident in recorded music over the course of the last century, several differently-tuned Es in between the E-flat and E-natural of the Western Chromatic scale are used, that vary according to the types of maqams and ajnas used, and the region in which they are used. Practical treatment Musicians and teachers refer to these in-between notes as quarter tones, using "half-flat" or "half-sharp" as a designation for the in-between flats and sharps, for ease of nomenclature. Performance and teaching of the exact values of intonation in each jins or maqam is usually done by ear. It should also be added, in reference to Habib Hassan Touma's comment above, that these quarter tones are not used everywhere in the maqamat: in practice, Arabic music does not modulate to 12 different tonic areas like the Well-Tempered Klavier. The most commonly used quarter tones are on E (between E and E), A, B, D, F (between F and F), and C. Vocal traditions Arab classical music is known for its famed virtuoso singers, who sing long, elaborately ornamented, melismatic tunes, coloraturas unheard in any other musical genres and are known for driving audiences into ecstasy. Its traditions come from pre-Islamic times, when female singing slaves entertained the wealthy, inspired warriors on the battlefield with their rajaz poetry, and performed at weddings. A vast number of female Arab vocalists are mezzo-sopranos who possess darker and richer tones than generic Soprano voices as a result of having thicker vocal folds and larger larynx. Instruments and ensembles The prototypical Arabic music ensemble in Egypt and Syria is known as the takht, and includes, (or included at different time periods) instruments such as the 'oud, qānūn, rabab, ney, violin (introduced in the 1840s or 50s), riq and dumbek. In Iraq, the traditional ensemble, known as the chalghi, includes only two melodic instruments—the jowza (similar to the rabab but with four strings) and santur—accompanied by the riq and dumbek. The Arab world has incorporated instruments from the West, including the electric guitar, cello, double bass and oboe, and incorporated influences from jazz and other foreign musical styles. The singers have remained the stars,