Listening to Qur’aan from a CD whilst on the bus

The Qur’aan is the word of Allaah which was revealed
to Muhammad

(peace and blessings of Allaah be upon him). It is mustahabb to read
it and recite it frequently. This is one of the means of raising one’s
status in Paradise, as it was narrated in the hadeeth of ‘Abd-Allaah
ibn ‘Amr ibn al-‘Aas (may Allaah be pleased with them both) that the
Prophet

(peace and blessings of Allaah be upon him) said: “It will be said to
the companions of the Qur’aan (i.e., those who read it much), ‘Read
and rise in status, recite as you used to recite in the world, for your
status will be commensurate with the last aayah you read.’” 

Likewise, listening to the Qur’aan is also mustahabb,
as the Prophet

(peace and blessings of Allaah be upon him) listened to the recitation
of Abu Moosa al-Ash’ari, and he said to him, “If only you could have
seen me when I was listening to your recitation yesterday.” And the
Prophet

(peace and blessings of Allaah be upon him) asked ‘Abd-Allaah ibn Mas’ood
(may Allaah be pleased with him) to recite the Qur’aan to him. ‘Abd-Allaah
said, “Should I recite it to you when it was revealed to you?” The Messenger

(peace and blessings of Allaah be upon him) said, “I like to hear it
from others.” 

So your listening to the Qur’aan on CD, as you asked
about, or from a tape recorder or on the radio or TV, comes under the
same ruling (i.e., it is mustahabb), whether that is at home, in the
car, on the bus  or in any other appropriate place. So long as
you focus on it and do not listen to it whilst doing something else,
you will be rewarded for listening. And Allaah knows best.