Modern Electrics, May, 1910, page 63 (photograph is from "A Review of Radio" by Lee DeForest, page 333 of the August, 1922 issue of Radio Broadcast):
Radio Telephone Experiments
A VERY interesting experiment was held on the afternoon of February 24th, by Dr. Lee DeForest in the transmission of music and operatic selections by wireless. The operatic selections were sung by Mme. Mariette Mazarin, the new star of the Manhattan Opera Company, whose first American interpretation of "Elektra" occasioned much comment by the music loving world.
This demonstration holds particular interest as it is the first successful one of its kind ever held and is one more step forward to prove that in the near future we will have "Wireless Music."
The transmitting station was located at the DeForest laboratory, near the Grand Central Station, N. Y. The operatic selections and music were clearly heard at the Metropolitan Life Building over a mile away and at the inventor's Newark, N. J. station, as well as by some hundred or more amateurs within a 20 mile range.
Among those present at the Metropolitan Life Building were the well known inventor Prof. Hudson Maxim, John T. Murphy, the New York Tenement House Commissioner, and a number of singers of the Manhattan Opera Company.
The first song Mme. Mazarin sang was the Aria from "Carmen." The listeners at the Metropolitan Life Building station, not being familiar with the notes as received from the wireless telephone, expressed great surprise at the clearness of the articulation. As is well known, an operatic selection is particularly hard to transmit by other medium than the natural sound striking distance, due to the extreme high and low notes reached by the singer's voice. This point, however, was not noticeable over the wireless telephone. Every intonation of the singer's voice was brought out clearly. The writers noticed the difference between the wire and wireless by first listening over the wire telephone and then over the wireless. Over the wire line the received notes were louder but the wireless brought out the vowel sounds with a "velvety" tone. For the benefit of those interested on the technical side it will be of interest to state that this difference is due to the distorting effect the wire line has to the telephonic voice current; the other, being the natural conducting medium, has no distorting effect on the wave, consequently we get the received tone in all its beauty.
The Prima-donna, when informed by the Metropolitan Station, the Newark Station, and a number of outlying ships, of the success of her first song responded with selections from "Elektra" to the great enjoyment of the distant listeners.
After the exhibition Mme. Mazarin and the audience became the guests of the Metropolitan Life Insurance Company and were shown the wonders of the building and allowed to view Manhattan from the tower, some 600 feet above Madison Square. Through the fog and distance could be seen the tower of the station from which the music was transmitted.
The new muffled spark system was explained to the audience by Mr. C. C. Heselton, the tower operator. He demonstrated the actual working utility by getting into immediate communication with Chicago, Washington, and Key West.