Listening to music is haraam, whether in Ramadaan or at other times, but it is more forbidden in Ramadaan, and is a greater sin, because fasting does not only mean refraining from eating and drinking, rather it means attaining piety or fear of Allaah, and it means that all the physical faculties should refrain from disobeying Allaah. 

Allaah says (interpretation of the meaning):

“O you who believe! Observing As-Sawm (the fasting) is prescribed for you as it was prescribed for those before you, that you may become Al-Muttaqoon (the pious)”

[al-Baqarah 2:183]

And the Prophet (peace and blessings of Allaah be upon him) said: “Fasting does not just mean (abstaining) from eating and drinking, rather fasting means (abstaining) from idle and obscene talk…”

Narrated by al-Haakim who said: This hadeeth is saheeh according to the conditions of Muslim. 

See also question no. 37989 

The saheeh Sunnah of the Prophet (peace and blessings of Allaah be upon him) clearly indicates that listening to musical instruments is haraam. 

Al-Bukhaari narrated in a mu’allaq report that the Prophet (peace and blessings of Allaah be upon him) said: “There will be among my ummah people who regard adultery, silk, pork and musical instruments as permissible…” Al-Tabaraani and al-Bayhaqi said that this was a mawsool report. 

This hadeeth indicates that musical instruments are haraam in two ways: 

1 – The Prophet (peace and blessings of Allaah be upon him) said, “[they] will regard… as permissible.” This clearly indicates that the things mentioned are haraam, but those people will regard them as permissible. 

2 – Musical instruments are mentioned in conjunction with things that are definitely haraam, namely adultery (zina) and alcohol. If it were not haraam it would not have been mentioned alongside them. 

See al-Silsilah al-Saheehah by al-Albaani , hadeeth no. 91. 

The believer should make the most of this blessed month and turn to his Lord. He should repent to Allaah and give up haraam things that he was in the habit of doing before Ramadaan, so that Allaah might accept his fast and set his affairs straight.

And Allaah knows best.