Miyoko Kawahara, 59, was sentenced by the Osaka High Court, revoking an initial ruling that had given her a one-year prison term, court spokesman Takanao Kawasaki said.
Kawahara in Heguri, Nara Prefecture (state) in western Japan, was accused of causing insomnia and headaches to her next-door neighbor by playing loud dance music almost 24 hours a day on a portable stereo she had pointed at her neighbor's house, six meters (20 feet) away.
She was arrested on April 11, 2005. The two women had had a number of disagreements that police did not elaborate on.
"The defendant ignored calls by local authorities and continuously played music at a high volume for some 29 months," Kyodo News agency quoted presiding Judge Hiroshi Furukawa as telling the court.
In handing down a longer prison term than a local court ruling in April, this year, Furukawa told the court that the defendant "still maintains a hostile attitude toward the victim and it is highly likely she will commit the crime again," Kyodo said.
Doctors had diagnosed the neighbor as having insomnia and headaches they attributed to the noise. Kawahara started blasting the music in November 2002 and continued until her arrest.
Under Japanese law, those convicted of inflicting injury on another person face up to 10 years in prison and a fine of up to 300,000 yen (US$2,520; Ђ1,910).