A Montgomery County judge turned down yesterday two requests by defense attorneys that charges against Timothy Joseph Buzbee, accused of several rapes in the Aspen Hill area, be thrown out. The attorneys contended that authorities allegedly violated Maryland law and Buzbee's constitutional rights in investigating and charging him with the rapes.

Circuit Court Judge Rosalyn B. Bell ruled that police followed Maryland law properly and were fair to Buzbee last November when they conducted a telephone-calling session in which a 16-year-old rape victim was asked if she could identify the voice of the man who had attacked her in July 1981.

The girl was called to testify yesterday. It was the first time any of the victims of the rapes that terrorized the Aspen Hill community for 18 months has appeared at a public hearing in the case.

The girl told the court that two police officers investigating the case came to her home last November and telephoned nine land surveyors, engaging each in a conversation about getting some work done on a piece of property. Buzbee is a 26-year-old land surveyor from Frederick, Md.

One of the officers pretended to be a "Mr. Winter" and inquired about the services, while the teen-ager listened in on an extension phone, according to testimony.

She told the court that after the seventh call, she told the detectives she was "pretty sure" the voice on the line was that of her attacker.

In tapes played in the courtroom yesterday, the man in the seventh call identified himself as "Tim." Police testified that they later determined that the man on the phone was Buzbee, who was then under police observation.

The defense attorneys argued that the calling session was unfair to Buzbee, because the other men called did not have voices similar to Buzbee's. They also argued that the conversation had been illegally tape recorded.

Bell ruled against them on both counts, asserting that although the group of telephone voices "was not perfect," the police did nothing to assist the young victim in her identification.